IBM's Game Control Adapter was designed as something of an afterthought, a simple to use expansion card (for a programmer) as a way to provide for connecting a low-priority input device. It sat at port 201, supported four digital inputs, intended for buttons and four analog inputs, intended for paddles or joystick axes.
When it was released as one of the original expansion cards for the new IBM PC, it was perfectly adequate for the time. The Apple II joystick port operated in the same way but only supported three buttons. The Tandy Color Computer also supported four analog axes and four buttons, and its joysticks were later used in the mostly-PC compatible Tandy 1000 line. The Commodore VIC-20 only supported one Atari-style joystick or two Atari-style paddles. Only the Atari 400 and 800, with their four joystick ports, supported more game inputs.
In IBM's design, a joystick is a pair of potentiometers which are turned by moving the joystick. Each three-terminal, 100 kOhm potentiometer is connected through the joystick cable to a +5v line and a capacitor on the game control adapter. This capacitor is tied to an input on the NE558 Timer IC. The Timer compares the capacitance on its input with a reference capacitance, and outputs a 1 when the capacitance is not equal and a 0 when the capacitance is equal. The resistance value from the potentiometer determines how quickly the capacitor on the input will be charged. If the capacitor is turned to a lower resistance, the capacitor charges more quickly, and if turned to a higher resistance, the capacitor charges more slowly.
When the programmer wants to read the joystick position, he writes to port 201. This discharges the capacitors. Then the programmer reads and reads port 201 until there is a 1 for the axis he is trying to measure. The time taken for the value to become a 0 represents the position of the joystick. Many games have joystick calibration prompts requiring the player to move his stick to its maximum positions and its center to obtain the timing required to properly calibrate the stick.
Eventually the limits of the design began to emerge. The first was that the joystick had to be read several times to get an accurate measurement of the stick's position. This took a substantial portion of a 4.77MHz 8088 CPU's time. However, when there was only one CPU and one speed used in PC and compatibles, this was just an inconvenience, because the timing would be equivalent on all machines. For many simpler games, which relied on digital controls, fine measurement of the joystick axes was not an issue. However, when faster CPUs and clock speed began to emerge, joystick routines would consequently run faster. Thus routines would take 20% of the CPU's time an 8088 may only take 10% or less of the CPU's time on the more efficient 286. When CPU speeds began increasing to 6MHz, 8MHz and beyond, routines that were designed for the IBM PC would complete themselves far too quickly to get an accurate read of the joystick.
A second issue with the inherent accuracy of the components used to determine the joystick's position. Linear potentiometers such as used in the PC are not known for their rigorous accuracy. While the adjustment dials on each axis can help, they can shift or loosen over time. Moreover, the housings containing the resistive element and wiper are not hermetically sealed or anything close to it. Dust and dirt and oils over time can seep in and cause jittery or inaccurate reads. Wear on the resistive element can make it harder for the stick to give an accurate resistance.
IBM gave a formula to measure the time the stick would take to charge the capacitor at any given resistance (0-100). When it released the IBM PC AT, with its 6MHz 80286 CPU, it introduced Int 15, subfunction 84 to give a BIOS routine to read the joystick. Unfortunately, the clone PC makers had already spent substantial time and money cloning the original IBM PC BIOS, and this new BIOS call did not necessarily make it into every clone. Tandy 1000s do not support it. The advantage of the function was to give reliable reads because the routine was tied to the processor and speed(s) which the system board was designed to run.
Other companies tried to offer solutions to these problems. Tandy 1000 joysticks used the design from the Tandy Color Computer. Instead of using the potentiometers as variable resistors, Tandy uses them as voltage dividers by connecting the third terminal to ground. Inside the machine, the voltage is compared to a voltage ramp which, when port 201 is written to, is charged from 0v to +5v in a set period of time. When the voltage ramp is greater than the voltage from the joystick, a 0 is reported. This method has been said to give more precise and less jittery results than the timer-resistance method used on a true PC.
The Amstrad PC-1512 gave a unique solution to the joystick problem. It supported one Atari-style digital joystick with two buttons. This joystick plugged into the keyboard. The directionals and buttons for the joystick were assigned to unique keyboard scancodes 7C-77. However, when reported by the BIOS, pressing the directionals would give scancodes assigned to the cursor keys on the numeric keypad. Since many, many games used the keypad cursor control keys for movement, this was a highly compatible way to implement digital input. It would not work if the program read directly from the keyboard input port instead of the BIOS unless the program was Amstrad-aware. The two joystick buttons could be assigned to represent any key through the use of a program which would write to the Amstrad's non-volatile RAM. This memory would retain the buttons' settings until the next time the buttons' settings were changed.
When the Sound Blaster came along, it implemented a standard joystick port. Until the Sound Blaster 16, the port did not change. In the Sound Blaster 16, the old DIP-style NE558 timer was replaced with surface mounted components, which presumably have lower latencies which work better with faster processors. The Gravis Ultrasound implemented a hardware version of a speed adjustable gameport, and came with a program to adjust the sensitivity of the gameport without the use of an external dial or jumper.
Other companies made speed-adjustable gameports. In these gameports, a dial would be routed outside the computer to adjust the speed of the gameport. In the Thrustmaster ACM Game Card, the dial was a potentiometer which would adjust the resistance going to the reference capacitor. The ACM Game Card had a second joystick interface at port 209, requiring a second NE558. The dial controls the resistance for both reference capacitors.
The Gravis Gamepad was very popular in the early 90s because it provided four buttons and a NES-style D-pad. However, inside the Gravis Gamepad were transistors to convert the digital values of a D-pad into the analog resistance values expected by the PC gameport. Essentially pressing one side of the pad would give the maximum resistance value of the axis, the other side would give the minimum resistance value and not pressing the pad would give the middle of the resistance value.
Later joysticks, like the Gravis Gamepad Pro and the Microsoft Sidewinder gamepads would give options for truly digital controller with more than four buttons. These sticks would use the gameport to send binary codes to the program. The downside is that a DOS program had to have specific support for the gamepad, or the digital functionality of the gamepad would only work in Windows 95 with a driver.
Another late innovation was to take inspiration from computer ball mice. Computer mice and trackballs use optical rotary encoders to track movement, just like the dials on most arcade machines, the Atari driving controller and the N64 thumbstick. Reading from the encoders is much more reliable than the timer-potentiometer method and not prone to speed sensitive issues or the same kind of wear. The Microsoft Sidewinder 3D Pro had this function and many buttons, but unless a DOS program understood it, it had to emulate the analog potentiometer method
Once IBM ceded leadership of the PC market, no other company came up with a standardized digital gameport solution. Eventually, USB input devices of all kinds, gamepads, joysticks, driving wheels, rudder pedals, throttles, yokes put all the speed issues to software. However, USB really didn't catch on until Windows 98, so for almost twenty years game players had to deal with the analog gameport.
Saturday, March 8, 2014
Friday, March 7, 2014
Tutorial : Compiling DOSBox SVN with Screenshot, Video Capture and IPX/Modem Support in Windows
DOSBox is a wonderful program, but in case you haven't noticed, the last official release, 0.74, is rapidly approaching its fourth birthday (05/12/2010). This is by far the longest time span between releases of the program. But DOSBox has not been sitting idly by, the developers have continued to fix bugs and add new features. While it is easy enough to find a pre-compiled version of the latest SVN, it may not be able to support screenshots without crashing (EmuCR), has more options in the config file than an average DOSBox user may need (DOSBox-X, Yhkwong's build) or simply won't have the features of that particular patch you are looking for. Until the development team releases 0.75, this is the closest you can get.
This tutorial is intended to guide a beginner through the compiling process in order to obtain a fully featured build of DOSBox SVN with important optional features such as IPX and Modem support and Screenshot and Video Recording in Windows. I have omitted adding the debugger features, if you need them, then this tutorial is probably too basic for you. To include the debug features, you need the curses library, and the best library for implementing the debugger in Windows is the pdcurses 3.4 library.
1. The Compiler
This tutorial assumes you are running DOSBox on some modern version of Windows and using an x86 CPU. (No Windows RT.) Since we will be using a Microsoft product to compile the source code, it will not work on any other system. It is easy enough to compile a DOSBox with the basic features. There is a good tutorial on how to do it in Visual Studio 2008 Express Edition. You can find it here and you may wish to consult with it if anything in this tutorial is unclear : http://www.dosbox.com/wiki/Building_DOSBox_with_Visual_C_2008_Express
I am indebted to the author, for this is the way I learned how to compile DOSBox, being a Microsoft loyalist since I first used a PC compatible in the early 90s. You can also use MinGW and MSYS, but that is a Unix/Linux approach utterly foreign to me (and I could never figure it out anyways).
VS2008 is getting a bit old in the tooth, and some of the more modern project files do not really support VS2008. So in this tutorial, I will be using Visual Studio 2010 Express, also freely downloadable from Microsoft. Virtual Studio includes Visual C++. Find it here :
http://www.visualstudio.com/en-us/downloads#d-2010-express
The installer will download the program and the modules it needs and will install them. It will also set file associations for the files we will be using.
2. The Source Code
Now, you need the source code. First start with the current DOSBox SVN, found here :
http://source.dosbox.com/dosboxsvn.tgz
You should use a program like 7zip to uncompress this file. It is doubly compressed. Please see my DOSBox patching guide if you want to add any patches, as you can at this stage :
http://nerdlypleasures.blogspot.com/2014/02/patching-dosbox-for-beginners.html
Next, you will need the Simple Directmedia Layer (SDL) to build libraries that DOSBox needs to function. DOSBox is only compatible with the 1.2 versions and the last version of SDL is 1.2.15. However, you should obtain the source code for 1.2.14, which is the last SDL 1.2 version that will compile easily in VS2010. You can download it here :
http://www.libsdl.org/release/SDL-1.2.14.zip
3. Optional Libraries
If you want to add the optional features to your compiled DOSBox, you will need some more source code to build libraries.
1. For Modem/IPX support, you need SDL_net. SDL_net's mirrors SDL's versions, and the most current version that will compile easily in VS2010 is 1.2.7. Get it here :
http://www.libsdl.org/projects/SDL_net/release/SDL_net-1.2.7.zip
Now what you have obtained above is the easy part. For working screenshots and video recording, you will need to compile libpng and zlib libraries from source. After that, then you compile DOSBox.
For libpng, the current stable source is 1.6.9. You can obtain it here :
http://prdownloads.sourceforge.net/libpng/lpng169.zip?download
You use libpng to compile both libpng.lib and zlib.lib, but for the latter, you need the zlib source code, and specifically 1.2.5 (even though 1.2.8 is the most recent version, but libpng expects 1.2.5). You can obtain 1.2.5 here :
http://www.winimage.com/zLibDll/zlib125.zip
4. Directory Setup
Once you have installed VS2010 and downloaded your source code and libraries, you need to put the source somewhere. Make a folder like \Project and unzip your source code and libraries so they look like this :
\Project\dosboxsvn
\Project\lpng169
\Project\SDL_net-1.2.7
\Project\SDL-devel-1.2.14
\Project\zlib-1.2.5
This will be important for the next step and make it easier to point the compiler to the various include and library files later on.
5. Compiling libpng.lib and zlib.lib
Go to \Project\lpng69\projects\vstudio\libpng and double click on libpng.vcxproj A vcxproj file is a Project File that tells a compiler how to build code. This will start the compiler. You should see Solution Explorer on the left hand side of the program. There are seven projects here, but we only need two of them. Right click on Solution 'vstudio' (7 projects), click on Properties and check the button that says Multiple startup projects: Set libpng and zlib to Start and the rest to None. Press Apply and OK.
Libpng relies on zlib, so we want to make sure zlib is compiled first. Right click on libpng in the Solution Explorer and go to Project Dependencies. In the drop down box, select libpng and make sure there is a checkmark next to zlib in the box below and none on any other box. Then click on the Build Order tab and you should see that zlib comes first and libpng comes second.
Next right click on Solution 'vstudio' (7 projects) and click on Configuration Manager. Under Active solution configuration: click Release Library. In the box below, next to libpng and zlib, change the Configuration to Release Library. For the other options, uncheck the boxes next to the Build so they will not be compiled. Do not worry if they compile anyway, these extra projects are mainly for testing.
Next, in the Solution Explorer right click on libpng and go to properties. On the left hand side, you should see a line called Configuration Properties. On the right side of the window, you will see a line that says Configuration Type. Click on the dropdown box next to it and set it to Static library (.lib) if it is not already.
Then click on VC++ Directories. The window here is a bit small for what you need to do, but be very careful here. Clicking on the wrong thing will wipe out the default directory entries, and if you do that the compiler will not know where to find the code it needs to compile.
Next to the line that says Include Directories, click once on the box after the partition. This will show a down arrow button. Click on that once and then click on On the next window, click on the icon of a file with an asterisk in the corner, then click on the box with the ... On the Select Directory Window, navigate to the directory with the zlib Include files. The directory is typically : \Project\zlib-1.2.5. When done, click OK.
To compile the libraries, hit F7. In the output window, you will see the compiler crunch code and turn it into libpng.lib and zlib.lib. If you succeed, the compiler will indicate where the .lib files are located. If you fail, then the compiler will report an error and your files will not be built. In this example, you can find the .lib files in \Project\lpng169\projects\vstudio\Release Library\ as zlib.lib and libpng16.lib.
6. Compiling SDL and SDL_net
In this guide, I have completely avoided using developer libraries. While there are appropriate Visual C ++ developer libraries that work with VS2010 available for SDL and SDL_net, I think its best to compile your own libraries. Since you have to do this for libpng and zlib, you already should begin to get a feel for how to incorporate include and library directories. Compiling your own libraries can improve DOSBox performance and compatibility with your particular system.
To compile SDL, you will need the DirectX SDK. The DirectX 10 SDK from June 2010 seems compatible, and you can get it here :
http://www.microsoft.com/en-us/download/details.aspx?id=6812
You only need to install the libraries. The installer may give an error if the rest of the components aren't installed, but the libraries will be installed. You will be able to find them typically in C:\Program Files (x86)\Microsoft DirectX SDK (June 2010)
Now, in the SDL-1.2.14 directory, there will be a zip file named VisualC.zip. Unzip it so that you can see files in the next level subdirectory. Go into that subdirectory and open the file SDL.sln. This is a solution file used by older versions of Visual C++ to build a project. VS2010 will run a conversion tool that will convert it into something it can manage properly. Click on Next and then Finish. You may see some warnings but you shouldn't see any errors.
In the resulting Solution Explorer, you will see two projects, SDL and SDLmain, and you will need to compile both of them. First, right click on Solution 'SDL' (2 projects) and go to properties. Then click on the button that says Configuration Manager. From the Active solution configuration: dropdown menu, click on release, and for the Configuration menu drop downs next to SDL and SDLmain, set them both to release. Close the Configuration Manager. At this point, the Configuration dropmenu should show Active(Release). Click on Apply and then OK.
Next, in the Solution Explorer right click on SDL and go to properties. On the left hand side, you should see a line called Configuration Properties. On the right side of the window, you will see a line that says Configuration Type. Click on the dropdown box next to it and set it to Static library (.lib) if it is not already. DOSBox needs the libraries to compile, and SDL should still create an SDL.dll when you compile it.
Then click on VC++ Directories. This is where you add the DirectX SDK libraries you installed at the beginning of this step Next to the line that says Include Directories, click once on the box after the partition. This will show a down arrow button. Click on that once and then click on On the next window, click on the icon of a file with an asterisk in the corner, then click on the box with the ... On the Select Directory Window, navigate to the directory with the DirectX SDK Include files. The directory is typically : \Program Files (x86)\Microsoft DirectX SDK (June 2010)\Include When done, click OK.
On the line that says Library Directories, you are going to do almost the same thing. This time, you want to add the directory for the DirectX SDK Library files. The directory is typically : \Program Files (x86)\Microsoft DirectX SDK (June 2010)\Lib\x86. Make sure you select the x86 (for 32-bit) and not the x64 (64-bit, DOSBox doesn't like 64-bit code). Once you are done, you can press OK to get back to the Solution Explorer. Now press F7 and you should be have created sdl.lib and sdlmain.lib in their respective Release directories, \Project\SDL-1.2.14\VisualC\SDL\Release and \Project\SDL-1.2.14\VisualC\SDLmain\Release
SDL_net requires the SDL libraries, which is why we compiled the SDL libraries first. Like with SDL, you will need to unzip the VisualC.zip file and convert the solution file SDL_net.sln. Set SDL_net to Release in the Configuration Properties.
Open the SDL_net properties page, set the Configuration Type to Static library (.lib) and then click on VC++ Directories. For the Include Directories, you need to add the directory containing the SDL Include files. They can be typically found here : \Project\SDL-1.2.14 Next you need to add the directories containing the SDL Library files. These are \Project\SDL-1.2.14\VisualC\SDL\Release and \Project\SDL-1.2.14\VisualC\SDLmain\Release. You need to add both. After you have done all this, you can exit the properties window and press F7 to compile. You should end up with sdl_net.lib.
7. Setting Up the DOSBox Compiling Environment
Now that you have all your libraries, you can compile as full a DOSBox as you like. Navigate to \Project\dosboxsvn\dosbox\visualc_net and click on dosbox.vcxproj
In the Solution Explorer Window, right click on dosbox. Set the active configuration to Release using the Configuration drop box and the Configuration Manager button first.
In the VC++ Directories, you will need to add the following directories to the Include Directories :
\Project\lpng169
\Project\SDL_net-1.2.7
\Project\SDL-1.2.14\include
\Project\zlib-1.2.5
\Program Files (x86)\Microsoft DirectX SDK (June 2010)\Include
If you are compiling code specific to Windows, you may also need to include a directory like :
\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\sys
You will need to add the following directories to the Library Directories :
\Project\lpng169\projects\vstudio\Release Library\
\Project\SDL_net-1.2.7\VisualC\Release
\Project\SDL-1.2.14\VisualC\SDL\Release
\Project\SDL-1.2.14\VisualC\SDLmain\Release
\Program Files (x86)\Microsoft DirectX SDK (June 2010)\Lib\x86
On the left side of the Property Page, click on C/C++ and then on General. On the line that says Treat Warnings As Errors, click on the box next to it and set it to No (/WX-) The compiling process will give many warnings, and if this is not set these warnings will cause the build to fail.
Next click on Linker and next to the Force File Output, click on the box next to it and select Multiply Defined Symbol Only (/FORCE:MULTIPLE). Next to the Treat Linker Warning As Errors, click on the box next to it and select No (/WX:NO). These "errors" and warnings are not going to affect a compiled DOSBox, but they certainly will stop DOSBox from compiling correctly.
Finally, underneath Linker, click Input. The following line needs to be present :
dinput8.lib;dxguid.lib;libpng16.lib;sdl_net.lib;opengl32.lib;winmm.lib;sdlmain.lib;sdl.lib;ws2_32.lib;zlib.lib;%(AdditionalDependencies)
Many of these items are already present. You will need to add dinput8.lib and dxguid.lib and rename libpng.lib to libpng16.lib. Since the space is very small, you should check the spelling and formatting very carefully. Each library, including the last, needs a semicolon ; after it.
8. Adjusting the DOSBox Code and compiling
In the Solution Explorer, clock on Source Files and then click on visualc and then double click on config.h. The code listing will appear to the right. If you are not compiling with IPX and Modem support, then change the values from 1 to 0 in the lines :
#define C_MODEM 1
#define C_IPX 1
If you are not compiling with screenshot and video recording support, change the value from 1 to 0 in the
line :
#define C_SSHOT 1
Next, for a speed boost, change the value from 0 to 1 in the line :
#define C_CORE_INLINE 0
Finally, you should see in the Solution Explorer a file called winres.rc. Right click on that and select View Code Change the line that says #include "afxres.h" to #include "Windows.h"
In the Solution Explorer, right click on dosbox, go to properties an then the Configuration Manager. Makes sure the Active solution configuration and the dosbox project configuration are both set to Release, NOT Debug. Release builds are faster than debug builds. Debug DOSBox builds exhibit an annoying issue with the Adlib music where it will stutter unless the cycle count is set very low in DOSBox. After you close the Configuration Manager window, you should see in the Configuration drop down menu Active(Release). Exit the dosbox Property pages.
Now you are ready to compile. Hit F7 and be prepared to wait. If you are successful, you will have a dosbox.exe in \Project\dosboxsvn\dosbox\visualc_net\Release. You probably will not need any .dll files since the libraries should be statically linked within the DOSBox executable, but if you do, you can obtain them from the official 0.74 DOSBox.
DOSBox will generate a .conf file on its first run if one is not present. Look in the status window to find it and move it to the directory in which you will use DOSBox. It is typically buried in AppData on Windows Vista/7/8. It will save screenshots and other captures to a folder named capture, but by default will save them to the same place as it wrote the .conf file.
If you are using Windows 8.1, you will find that the mouse movement will be extremely jerky when using this build. This is due to some changes Microsoft made in handling mouse input. To fix the problem, apply the appropriate patch for your OS (32-bit or 64-bit) from here : http://support.microsoft.com/kb/2908279
This tutorial is intended to guide a beginner through the compiling process in order to obtain a fully featured build of DOSBox SVN with important optional features such as IPX and Modem support and Screenshot and Video Recording in Windows. I have omitted adding the debugger features, if you need them, then this tutorial is probably too basic for you. To include the debug features, you need the curses library, and the best library for implementing the debugger in Windows is the pdcurses 3.4 library.
1. The Compiler
This tutorial assumes you are running DOSBox on some modern version of Windows and using an x86 CPU. (No Windows RT.) Since we will be using a Microsoft product to compile the source code, it will not work on any other system. It is easy enough to compile a DOSBox with the basic features. There is a good tutorial on how to do it in Visual Studio 2008 Express Edition. You can find it here and you may wish to consult with it if anything in this tutorial is unclear : http://www.dosbox.com/wiki/Building_DOSBox_with_Visual_C_2008_Express
I am indebted to the author, for this is the way I learned how to compile DOSBox, being a Microsoft loyalist since I first used a PC compatible in the early 90s. You can also use MinGW and MSYS, but that is a Unix/Linux approach utterly foreign to me (and I could never figure it out anyways).
VS2008 is getting a bit old in the tooth, and some of the more modern project files do not really support VS2008. So in this tutorial, I will be using Visual Studio 2010 Express, also freely downloadable from Microsoft. Virtual Studio includes Visual C++. Find it here :
http://www.visualstudio.com/en-us/downloads#d-2010-express
The installer will download the program and the modules it needs and will install them. It will also set file associations for the files we will be using.
2. The Source Code
Now, you need the source code. First start with the current DOSBox SVN, found here :
http://source.dosbox.com/dosboxsvn.tgz
You should use a program like 7zip to uncompress this file. It is doubly compressed. Please see my DOSBox patching guide if you want to add any patches, as you can at this stage :
http://nerdlypleasures.blogspot.com/2014/02/patching-dosbox-for-beginners.html
Next, you will need the Simple Directmedia Layer (SDL) to build libraries that DOSBox needs to function. DOSBox is only compatible with the 1.2 versions and the last version of SDL is 1.2.15. However, you should obtain the source code for 1.2.14, which is the last SDL 1.2 version that will compile easily in VS2010. You can download it here :
http://www.libsdl.org/release/SDL-1.2.14.zip
3. Optional Libraries
If you want to add the optional features to your compiled DOSBox, you will need some more source code to build libraries.
1. For Modem/IPX support, you need SDL_net. SDL_net's mirrors SDL's versions, and the most current version that will compile easily in VS2010 is 1.2.7. Get it here :
http://www.libsdl.org/projects/SDL_net/release/SDL_net-1.2.7.zip
Now what you have obtained above is the easy part. For working screenshots and video recording, you will need to compile libpng and zlib libraries from source. After that, then you compile DOSBox.
For libpng, the current stable source is 1.6.9. You can obtain it here :
http://prdownloads.sourceforge.net/libpng/lpng169.zip?download
You use libpng to compile both libpng.lib and zlib.lib, but for the latter, you need the zlib source code, and specifically 1.2.5 (even though 1.2.8 is the most recent version, but libpng expects 1.2.5). You can obtain 1.2.5 here :
http://www.winimage.com/zLibDll/zlib125.zip
4. Directory Setup
Once you have installed VS2010 and downloaded your source code and libraries, you need to put the source somewhere. Make a folder like \Project and unzip your source code and libraries so they look like this :
\Project\dosboxsvn
\Project\lpng169
\Project\SDL_net-1.2.7
\Project\SDL-devel-1.2.14
\Project\zlib-1.2.5
This will be important for the next step and make it easier to point the compiler to the various include and library files later on.
5. Compiling libpng.lib and zlib.lib
Go to \Project\lpng69\projects\vstudio\libpng and double click on libpng.vcxproj A vcxproj file is a Project File that tells a compiler how to build code. This will start the compiler. You should see Solution Explorer on the left hand side of the program. There are seven projects here, but we only need two of them. Right click on Solution 'vstudio' (7 projects), click on Properties and check the button that says Multiple startup projects: Set libpng and zlib to Start and the rest to None. Press Apply and OK.
Libpng relies on zlib, so we want to make sure zlib is compiled first. Right click on libpng in the Solution Explorer and go to Project Dependencies. In the drop down box, select libpng and make sure there is a checkmark next to zlib in the box below and none on any other box. Then click on the Build Order tab and you should see that zlib comes first and libpng comes second.
Next right click on Solution 'vstudio' (7 projects) and click on Configuration Manager. Under Active solution configuration: click Release Library. In the box below, next to libpng and zlib, change the Configuration to Release Library. For the other options, uncheck the boxes next to the Build so they will not be compiled. Do not worry if they compile anyway, these extra projects are mainly for testing.
Next, in the Solution Explorer right click on libpng and go to properties. On the left hand side, you should see a line called Configuration Properties. On the right side of the window, you will see a line that says Configuration Type. Click on the dropdown box next to it and set it to Static library (.lib) if it is not already.
Then click on VC++ Directories. The window here is a bit small for what you need to do, but be very careful here. Clicking on the wrong thing will wipe out the default directory entries, and if you do that the compiler will not know where to find the code it needs to compile.
Next to the line that says Include Directories, click once on the box after the partition. This will show a down arrow button. Click on that once and then click on
To compile the libraries, hit F7. In the output window, you will see the compiler crunch code and turn it into libpng.lib and zlib.lib. If you succeed, the compiler will indicate where the .lib files are located. If you fail, then the compiler will report an error and your files will not be built. In this example, you can find the .lib files in \Project\lpng169\projects\vstudio\Release Library\ as zlib.lib and libpng16.lib.
6. Compiling SDL and SDL_net
In this guide, I have completely avoided using developer libraries. While there are appropriate Visual C ++ developer libraries that work with VS2010 available for SDL and SDL_net, I think its best to compile your own libraries. Since you have to do this for libpng and zlib, you already should begin to get a feel for how to incorporate include and library directories. Compiling your own libraries can improve DOSBox performance and compatibility with your particular system.
To compile SDL, you will need the DirectX SDK. The DirectX 10 SDK from June 2010 seems compatible, and you can get it here :
http://www.microsoft.com/en-us/download/details.aspx?id=6812
You only need to install the libraries. The installer may give an error if the rest of the components aren't installed, but the libraries will be installed. You will be able to find them typically in C:\Program Files (x86)\Microsoft DirectX SDK (June 2010)
Now, in the SDL-1.2.14 directory, there will be a zip file named VisualC.zip. Unzip it so that you can see files in the next level subdirectory. Go into that subdirectory and open the file SDL.sln. This is a solution file used by older versions of Visual C++ to build a project. VS2010 will run a conversion tool that will convert it into something it can manage properly. Click on Next and then Finish. You may see some warnings but you shouldn't see any errors.
In the resulting Solution Explorer, you will see two projects, SDL and SDLmain, and you will need to compile both of them. First, right click on Solution 'SDL' (2 projects) and go to properties. Then click on the button that says Configuration Manager. From the Active solution configuration: dropdown menu, click on release, and for the Configuration menu drop downs next to SDL and SDLmain, set them both to release. Close the Configuration Manager. At this point, the Configuration dropmenu should show Active(Release). Click on Apply and then OK.
Next, in the Solution Explorer right click on SDL and go to properties. On the left hand side, you should see a line called Configuration Properties. On the right side of the window, you will see a line that says Configuration Type. Click on the dropdown box next to it and set it to Static library (.lib) if it is not already. DOSBox needs the libraries to compile, and SDL should still create an SDL.dll when you compile it.
Then click on VC++ Directories. This is where you add the DirectX SDK libraries you installed at the beginning of this step Next to the line that says Include Directories, click once on the box after the partition. This will show a down arrow button. Click on that once and then click on
On the line that says Library Directories, you are going to do almost the same thing. This time, you want to add the directory for the DirectX SDK Library files. The directory is typically : \Program Files (x86)\Microsoft DirectX SDK (June 2010)\Lib\x86. Make sure you select the x86 (for 32-bit) and not the x64 (64-bit, DOSBox doesn't like 64-bit code). Once you are done, you can press OK to get back to the Solution Explorer. Now press F7 and you should be have created sdl.lib and sdlmain.lib in their respective Release directories, \Project\SDL-1.2.14\VisualC\SDL\Release and \Project\SDL-1.2.14\VisualC\SDLmain\Release
SDL_net requires the SDL libraries, which is why we compiled the SDL libraries first. Like with SDL, you will need to unzip the VisualC.zip file and convert the solution file SDL_net.sln. Set SDL_net to Release in the Configuration Properties.
Open the SDL_net properties page, set the Configuration Type to Static library (.lib) and then click on VC++ Directories. For the Include Directories, you need to add the directory containing the SDL Include files. They can be typically found here : \Project\SDL-1.2.14 Next you need to add the directories containing the SDL Library files. These are \Project\SDL-1.2.14\VisualC\SDL\Release and \Project\SDL-1.2.14\VisualC\SDLmain\Release. You need to add both. After you have done all this, you can exit the properties window and press F7 to compile. You should end up with sdl_net.lib.
7. Setting Up the DOSBox Compiling Environment
Now that you have all your libraries, you can compile as full a DOSBox as you like. Navigate to \Project\dosboxsvn\dosbox\visualc_net and click on dosbox.vcxproj
In the Solution Explorer Window, right click on dosbox. Set the active configuration to Release using the Configuration drop box and the Configuration Manager button first.
In the VC++ Directories, you will need to add the following directories to the Include Directories :
\Project\lpng169
\Project\SDL_net-1.2.7
\Project\SDL-1.2.14\include
\Project\zlib-1.2.5
\Program Files (x86)\Microsoft DirectX SDK (June 2010)\Include
If you are compiling code specific to Windows, you may also need to include a directory like :
\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\sys
\Project\lpng169\projects\vstudio\Release Library\
\Project\SDL_net-1.2.7\VisualC\Release
\Project\SDL-1.2.14\VisualC\SDL\Release
\Project\SDL-1.2.14\VisualC\SDLmain\Release
\Program Files (x86)\Microsoft DirectX SDK (June 2010)\Lib\x86
On the left side of the Property Page, click on C/C++ and then on General. On the line that says Treat Warnings As Errors, click on the box next to it and set it to No (/WX-) The compiling process will give many warnings, and if this is not set these warnings will cause the build to fail.
Next click on Linker and next to the Force File Output, click on the box next to it and select Multiply Defined Symbol Only (/FORCE:MULTIPLE). Next to the Treat Linker Warning As Errors, click on the box next to it and select No (/WX:NO). These "errors" and warnings are not going to affect a compiled DOSBox, but they certainly will stop DOSBox from compiling correctly.
Finally, underneath Linker, click Input. The following line needs to be present :
dinput8.lib;dxguid.lib;libpng16.lib;sdl_net.lib;opengl32.lib;winmm.lib;sdlmain.lib;sdl.lib;ws2_32.lib;zlib.lib;%(AdditionalDependencies)
Many of these items are already present. You will need to add dinput8.lib and dxguid.lib and rename libpng.lib to libpng16.lib. Since the space is very small, you should check the spelling and formatting very carefully. Each library, including the last, needs a semicolon ; after it.
8. Adjusting the DOSBox Code and compiling
In the Solution Explorer, clock on Source Files and then click on visualc and then double click on config.h. The code listing will appear to the right. If you are not compiling with IPX and Modem support, then change the values from 1 to 0 in the lines :
#define C_MODEM 1
#define C_IPX 1
If you are not compiling with screenshot and video recording support, change the value from 1 to 0 in the
line :
#define C_SSHOT 1
Next, for a speed boost, change the value from 0 to 1 in the line :
#define C_CORE_INLINE 0
Finally, you should see in the Solution Explorer a file called winres.rc. Right click on that and select View Code Change the line that says #include "afxres.h" to #include "Windows.h"
In the Solution Explorer, right click on dosbox, go to properties an then the Configuration Manager. Makes sure the Active solution configuration and the dosbox project configuration are both set to Release, NOT Debug. Release builds are faster than debug builds. Debug DOSBox builds exhibit an annoying issue with the Adlib music where it will stutter unless the cycle count is set very low in DOSBox. After you close the Configuration Manager window, you should see in the Configuration drop down menu Active(Release). Exit the dosbox Property pages.
Now you are ready to compile. Hit F7 and be prepared to wait. If you are successful, you will have a dosbox.exe in \Project\dosboxsvn\dosbox\visualc_net\Release. You probably will not need any .dll files since the libraries should be statically linked within the DOSBox executable, but if you do, you can obtain them from the official 0.74 DOSBox.
DOSBox will generate a .conf file on its first run if one is not present. Look in the status window to find it and move it to the directory in which you will use DOSBox. It is typically buried in AppData on Windows Vista/7/8. It will save screenshots and other captures to a folder named capture, but by default will save them to the same place as it wrote the .conf file.
If you are using Windows 8.1, you will find that the mouse movement will be extremely jerky when using this build. This is due to some changes Microsoft made in handling mouse input. To fix the problem, apply the appropriate patch for your OS (32-bit or 64-bit) from here : http://support.microsoft.com/kb/2908279
Thursday, March 6, 2014
IBM PCjr. Upgrades
IBM PCjr. Internal Modem
The IBM PCjr. Internal Modem fits in a special slot inside the PCjr. The Modem sits at COM1 and this is undoubtedly its most useful purpose in the modern era. The BIOS designates the internal serial port, with no modem installed, as COM1. The resources the serial port uses, I/O 278H and IRQ3, are those typically assigned to COM2. This causes programs no end of confusion, and usually a program like COMSWAP is used to redesignate the serial port as COM2.
The Internal Modem uses the resources typically assigned to COM1, I/O 3F8H and IRQ4. By installing one, even if you never intend to use it, the BIOS will assign the Modem to COM1 and the serial port to COM2.
If you want to use a serial mouse and you don't have the Internal Modem installed, you can use the Cutemouse v1.91 driver. You will need to use the following command line argument /S13. This tells the driver to use the device at COM1 and IRQ3.
IBM's PCjr. Internal Modem is based on the Novation 103 Smart Modem, which uses a command set somewhat different from the Hayes compatible command set most terminal emulator programs expect. However, once you learn the basic commands and how to implement them in a terminal emulator, it can be used, as it was intended, at 300 baud. It does not have any speaker on it, so the only way to know whether you have connected is to review the messages sent from the modem. All commands can be shortened to the first letter, like the Hayes command set in many instances.
To initialize the modem, use the command : I
To set the format, use the command : F. The modem supports the following serial data formats (data bits:parity:stop bit) :
0 - 7:M-1
1 - 7-S-1
2 - 7-O-1
3 - 7-E-1
4 - 8-N-1
The default is 7-E-1. M is Mark Parity, S is Space Parity, E is even Parity and O is Odd Parity. To set the format to 8-N-1, use the command : F 4. The initialize and format commands can be carried on the same command line, separated by a comma. Using an 8-bit speed will show more corrupt characters than using the 7-bit speed, but it is faster and more compatible with BBS terminals that still allow for dialup.
The command to dial is appropriately called "dial", and you type in the number after it. I would recommend putting a "w" just before the number to ensure the modem dials using tone rather than the old-fashioned pulse and add a short delay to avoid any confusion by noise at the line gets taken off the hook. This is a command to dial : D w15555555555.
The command to answer is : A. The hangup command is : H.
Any commands to the modem must be prefaced by a control character. The default character is 0E/Ctrl N. This is the equivalent of the AT control character of the Hayes commands. The command string must be terminated by a carriage return/Ctrl M, just like Hayes. However, there is no +++ equivalent, the modem will always view one of the 255 ASCII codes as a command code, but it does allow you to change the default ASCII value with the N command.
The program ProComm, 2.4.3, which was very popular back in the day, will work with the PCjr. Internal Modem. The default strings to enter in the setup menu look like these :
^N I, F 4 ^M
^N D w##########
^M
^N H ^M
If you have a phone service that uses a stuttering dial tone to indicate that you have new voicemail, this modem may interpret the stuttering signal as a BUSY signal and do nothing. Clear your voicemail.
Many of the few BBSes expect a faster transmission rate than 300 baud or a more robust modem solution. One BBS that more or less works is the Capitol City Online BBS out of Frankfort, KY. Its telephone number is 502-875-8938.
IBM PCjr. Parallel Printer Attachment
This sidecar adds one parallel port and was a very popular add-on for the PCjr, which did not come with a parallel port. The parallel port is a standard DB-25F connector, unlike virtually every port on the back of the PCjr. It uses the standard CGA LPT1 resources, I/O 378H and IRQ7. If there is no parallel printer sidecar installed, then the serial port will receive the LPT1 designation. When the parallel port is installed, the BIOS will reassign LPT1 to it. IBM did not allow the settings on the parallel port adapter to be changed, so only one parallel port is supported. There is a fairly simple mod to change the I/O to the LPT2 278H address, you can find it here : http://www.brutman.com/PCjr/lpt2_mod.html
The parallel port is a unidirectional port by default, capable of nibble transfers. There is an easy mod to make the parallel port bidirectional. This will double throughput when an external devices wants to send data through the parallel port to the computer. The instructions for the mod can be found here : http://www.brutman.com/PCjr/parallel_port.html This mod will also work with the ISA-based IBM PC Printer Adapter and the IBM Monochrome Display and Printer Adapter and probably all clones that implement a parallel port strictly using TTL logic.
The parallel port is useful for more than just connecting to printers, although it can do that too. I have connected it to a 2008 vintage Brother MFC-8860DN and it was able to print from DOS. It is far more useful to use with a 100MB zip drive or an Ethernet adapter like the Xircom PE3-10BC. The Xircom's packet driver (PE3PD.COM) and test program (PE3TEST.EXE) work just fine with an 8088 machine and a PCjr. The packet driver is initialized as follows for a PCjr. with an unmodified parallel port :
pe3pd sint=60 non
The non tells the adapter to operate in the non-Bidirectional mode (a.k.a. Unidirectional), and sint=60 assigns the Packet Driver services to software interrupt 60H. The driver can autodetect the presence of the adapter on any of the LPT assignments and the Interrupt.
Using the Xircom adapter, you can transfer files to and from the PCjr. with relative ease. There is a suite of TCP/IP utilities called mTCP, which you can get from here. http://www.brutman.com/mTCP/ The DHCP client utility especially useful for automatically obtaining all the critical information (IP, Gateway, Nameserver) from your route to connect to the Internet. I typically start up the packet driver and dhcp client in a batch file which I created (MTCP.BAT) and it looks like this :
c:\mtcp\pe3pd sint=60 non
set MTCPCFG=c:\mtcp\tcp.cfg
c:\mtcp\dhcp.exe
There are other useful utilities. The IRCJR functions as a basic Internet Relay Chat client. You can use it to chat on IRC. It will not download files from IRC though. I use it to connect to the Vintage Computer IRC channel on irc.slashnet.org, /join #vc. SNTP will obtain the time and date from an internet server and set the time and date in DOS. This is very useful for systems without a Real Time Clock or you want more exact time. There is also a Telnet client with ANSI emulation for all your text-based terminal needs. There is also a basic FTP client. It can copy (get) multiple files, but not sub-directories.
To actually use these utilities, you need to create a file called TCP.CFG. At a minimum, the following is required :
PACKETINT 0x60
HOSTNAME PCjr
The PACKETINT must correspond with the Packet Driver's software interrupt, but the HOSTNAME can be anything. DHCP will add or change the necessary configuration every time you start the DHCP server. Individual mTCP utilities will have their own settings in this file.
The most important utility is the FTP Server. This utility lets you operate your PCjr. as an FTP Server. The practical application of this utility is an easy and modern method to send from and receive files to your PCjr.'s (or any DOS machine) drives. You setup the FTP Server on the PCjr,'s end and use a modern FTP Client on your modern PC like Filezilla. This is what I use, and with a few tweaks to Filezilla, it works well.
In Filezilla, set the transfer type to binary, the maximum number of connections to 1, the timeout to 200 seconds and the speed limits to 25K/25K. If you have a bidirectional port, you can push the speeds higher, but 50KB/50KB is the max you will probably be able to get from a PCjr. A V20 or faster CPU will speed up transfer rates a bit. Filezilla expects to talk to a modern machine, and it runs so fast that the flow control will get screwed up waiting for the slow PCjr.
On the PCjr. FTP Server, I recommend the following lines added to TCP.CFG :
FTPSRV_PASSWORD_FILE ftppass.txt
FTPSRV_LOG_FILE log.txt
FTPSRV_EXCLUDE_DRIVES AB
FTPSRV_FILEBUFFER_SIZE 16
FTPSRV_TCPBUFFER_SIZE 16
FTPSRV_PACKETS_PER_POLL 10
The first two are required for FTP Server to run. The remainder give the maximum buffer sizes and exclude the floppy drives.
jrIDE
jrIDE is an amazing sidecar that was recently (2012) developed by PCjr. enthusiasts, mainly Alan Hightower. It combines 1MB of SRAM, a real time clock chip and can boot 16-bit IDE drives. It can support an IDE master and an IDE slave drive, and it can effectively support hard drives up to 8GB (the maximum of using DOS and FAT16).
The RTC is a Dallas 12887 module, and is socketed for replacement. The date and time is set by a program called rtc, loaded in the autoexec.bat file on startup. IRQ 1, 2 or 7 can be selected for its operation. I suggest IRQ2 because the parallel port uses IRQ7 and the keyboard on a regular PC uses IRQ1, which could possibly confuse some programs that are not PCjr-aware. The Speech Attachment also uses IRQ1. Using an IRQ really is not essential for this function.
In order to set the date and time, you will need a small program called rtc.com, available here:
http://www.retrotronics.org/svn/jride/trunk/prebuilt/jr/
To set the date and time for the RTC, first, set the correct date and time in DOS using the DATE and TIME commands. Next, run the rtc.com program with the /r switch. This will send the date and time you told DOS to the RTC. Finally, add the rtc.com program to your autoexec.bat file with the /d switch. Upon every bootup, this will fetch the correct date and time from the RTC and automatically set it in DOS.
The IDE header is at a right angle and has all 40 pins. Pins 1 and 2 are at the bottom of the board. The key pin can (via jumper) be used to provide +5v to power low-power devices like Disk On Module (DOM) devices or Compact Flash cards. The PCjr., without a power sidecar, is not likely able to supply sufficient power for a 2.5" or 3.5" hard disk drive. I found that even a DOM had difficulty when it was the third card in the system.
The jrIDE BIOS is based on the Universal XT-IDE BIOS, so it should be able to support drives up to 8.4GB in size supported by Int 13 and maybe higher if true LBA is used.. Practically speaking, the use of DOS (pre 7.1) is going to limit you to 4GB drives. You will need PC-DOS or MS-DOS 4.0 or better to use a primary partition (primary drive) greater than 32MB and logical drives greater than 32MB. With DOS 4.0 or above, you can have a primary partition of 2GB (C:) and one or more logical drives in the extended partition within the remaining 2GB (D:). With DOS 3.3, below, you will be limited at a maximum to a primary 32MB partition (C:) and 32MB logical drives in the extended partition, D:-Z: for 736MB total hard disk space. With PC-DOS 3.0-3.2, only one DOS 32MB partition is available for a C: drive per disk. DOS 2.1 allows only one 15MB partition for C:. Using DOS 5.0 or above requires patching the DOS system files as outlined here : http://www.brutman.com/forums/viewtopic.php?f=3&t=224&p=1978&hilit=stacks#p1978
Of that 1MB of RAM, you can have 736KB total conventional memory, even though the PCjr. only counts to 640KB on the startup screen. However, without a device driver loaded in config.sys, DOS will only see 128KB of RAM, and that is before it loads itself and the video buffer is taken into account. The remaining RAM is the slow RAM controlled by the video controller.
The device driver to use with the PCjr. and jrIDE is JRCONFIG.SYS v3.10 from PC Enterprises. The most basic use of it is to load it in config.sys like so :
DEVICE=C:\JRCONFIG.SYS -V64
When this driver is loaded with a jrIDE, it will give you 608KB of conventional memory free. Physically, this memory is between the first, slow 128KB and the video buffer window which starts at 736KB. The lower 128KB is reserved for DOS and the video memory. You can use what is left over for a RAM disk. RAM disks are especially important if you are using a null-modem to transfer data to or from a PCjr. because the machine lacks DMA.
A system booted to DOS with JRCONFIG v3.10 and no other drivers or an autoexec.bat loaded will report 753,664 total bytes (736KB) and 610,656 bytes free (596KB). You can also try an earlier version of the driver called JRCONFIG.DSK v2.14, which should require less RAM.
The driver has many command line switches, the only one that most people will need is -v64. This will allocate 64KB of video memory within a 32KB video page so that programs using the 320x200x16 and 640x200x4 modes will work.
The only major downside to using JRCONFIG is that it is not really compatible with Cartridge BASIC. REM out the line with JRCONFIG or simply rename config.sys when you need to use Cartridge BASIC and DOS. Cartridge BASIC is limited to 64KB free memory and freaks out if it is told there is more than 128KB in the system.
Since JRCONFIG uses software interrupt 60, which is the default software interrupt for many Ethernet DOS packet drivers, assign the packet driver to use a different interrupt.
You can find JRCONFIG here : http://www.brutman.com/PCjr/pcjr_downloads.html jrconfig.zip is the v2.14 version, jrcfg310.zip is the v3.10 version.
To obtain a jrIDE, join the PCjr. Web Forum, here : http://www.brutman.com/forums/ Be prepared to spend well over $100 to obtain an assembled one, and you may have to wait. The board assembly itself requires only through hole soldering, but the project is still quite the undertaking.
NEC V20
Most IBM PCjr. will have a socketed 8088 CPU, located underneath the disk drive. If you are unlucky and received one of the last units sold by IBM, the CPU will be soldered onto the motherboard. You can remove the 8088 CPU from the socket and replace it with a V20 CPU for a decent (10-15%) speed boost while retaining nearly 100% compatibility with software. The most common part number for the V20 is the NEC D70108. If you have a soldered CPU, you can always remove the CPU and solder in a 40-pin socket.
The V20, V30, 80186 and 80286 and later CPUs are not 100% compatible with 8086/8088 software because the 8086/8088 have undefined/illegal (as opposed to undocumented) opcodes whereas the later CPUs do not. The only game I am aware of, after a great deal of searching, that may not support the V20 PCjr. is Lode Runner, but every version of the game available for download works just fine with a V20. Every cartridge game for the PCjr. works fine with the V20.
Increasing the clock speed of the 8088 or V20 is not for the faint of heart. There is one 14.318MHz crystal on the PCjr that is used for all system timing. This includes the CPU clock speed, the 8253 Timer input and the OSC signal. In the PC it is arguably more difficult to overclock because the DMA chip uses the CPU CLK signal for its timing. Replace that crystal and all three frequencies, which are derived from an Intel 8284 Clock Generator chip, will change.
There is a PCB design called PC-SPRINT that essentially directs a higher clock solely to the CPU. It is a separate board which is piggybacked on the existing CPU socket. It has a separate crystal and a second 8284. Typically, speeds of 7.16MHz or 7.37MHz are stable, although some people have boasted of obtaining a 9.54MHz speed.
IBM PCjr. Speech Attachment
This sidecar contains a TMS5220 chip very similar to the chips used in the Speak & Spell toys of the time and sounds identical. It uses two methods to digitize and playback sound, LPC (linear predictive coding) and CVSD (continuously variable slope delta modulation). The TMS chip handles the LPC while the CVSD is handled by a MC3418. Interfacing to these chips is through an 8255 PPI and 8254 Timer. All audio output is routed through the system board multiplexer just like the 3-voice chip.
LPC allows for the use of compressed digitized samples and the sampling rate is of higher quality. The Sppech Attachment uses this method to play its built in vocabulary of 196 words, phrases and sound effects. Its 32K ROM chip resides at CE000-CFFFF. The voice playback of the vocabulary samples has an 8KHz sample rate. The built-in vocabulary is very easy to access in BASIC. You can add your own (compressed) vocabulary words with a computer that has a program that can encode the recorded sound into the format of the Speech Attachment.
CVSD allows for recording voice and sound through the microphone input and play it back. Normally voice recording is limited to disk size, but if you have a large hard disk, this will be less of a concern. The recording and playback speed through the microphone ranges from 1.8K-4.8K per second. CVSD encodes at 1 bit per sample, so that audio sampled at 38.4 kHz is encoded at 38.4 kbit/s. The default addresses used are FB98-FB9F, FF98 and FF9F. It also uses IRQ1.
The best program I have discovered to use the Speech Attachment is MAKETALK from PC Enterprises. It will allow you to play the vocabulary and build sentences for recording by an external device and also allow you to record and playback to the limits of your disk space.
IBM PC Compact Printer
IBM released this low-cost printer to go with its low cost entry system. It is a thermal printer and uses an 8-pin head. It has just one button for line feed and a power switch and LED. The printer uses the PCjr. serial BERG connector that plugs directly into the PCjr, but adapters exist that can convert it into a DB-25 connector for use with a regular serial port and a PC compatible.
This printer can print 56 characters per second, but only prints from left to right. It can print 80 characters per line in standard mode, and supports double width mode, compressed mode, compressed/double width mode and underlining. It prints all the 256 IBM ASCII and Extended ASCII characters except for the 64 block characters at 176-223. It also supports a 480-bit graphics mode.
The Compact Printer uses an 8.5" wide paper roll. The rolls typically are not perforated, so the user must cut or tear pages to length. The lack of perforations makes it ideal for banners and graphics. Staples and OfficeDepot sell 8.5" rolls, typically 98' or 164'. Thermal printers do not need ink ribbons, ink or toner cartridges, so their operational cost is strictly from the paper.
The printer has a data transfer rate of 1200bps and uses 1 start bit, 8 data bits, no parity and 2 stop bits. In order to obtain reliable operation, as in no missing or skipped characters, you should use the following parameters with the MODE command :
mode COM2: 1200, n, 8, 2, p
Without the IBM Parallel Printer Attachment, the BIOS assigns the serial port to LPT1. Thus devices printing only to LPT1 should not have a problem. If you have a Parallel Port attached, then it will be assigned to LPT1. You can redirect LPT1 to COM1 or COM2, depending on which your printer is designated, by the command :
mode LPT1:=COM1: or
mode LPT1:=COM2:
The last issue with this printer is loading the paper. First, you lift the smoky colored cover. Next, there is a tab on the left side that you push in, allowing the paper roll enough room to fit inside the housing. Fit the cardboard portion of the roll onto the two pegs. The end of the paper must be feeding upwards and counterclockwise. Release the latch on the side to let the printer allow the paper to be fed to the thermal head. Take the edge of the paper, fold it in a U shape, and guide it down behind the beige plastic bar. Use the paper feed button until the paper catches. Gently adjust the paper, once you can see it through the underside of the thermal element so that it is straight and then close the latch on the side to hold the paper in place. Make sure you have enough paper so that a little bit of paper appears over the plastic cover when you put it down.
Tandy Mod
One upgrade you may want to make to your system board is to make it more compatible with games that support the 160x200x16, 320x200x16 or 640x200x4 graphics modes only with a Tandy 1000. Some games (essentially just about every PC game released after 1985) will allow you to select Tandy graphics, but when you play these games on a stock PCjr., you will only see every other line. The Tandy mod will fix this problem. A good guide to the mod with instructions can be found here : http://vintagemashups.net/2011/12/ibm-pcjr-tandy-1000-graphics-mod/
Other problems may prevent a game from working on a PCjr., including when a game auto-detects a Tandy 1000, keyboard or joystick input issues, graphical anomalies due to the differences between the Tandy and PCjr. graphics controllers, disk-based copy protection failures. You may need to set the audio multiplexer to output 3-voice music before starting a game.
Of PCjr. games, the only game I know of that doesn't like the Tandy mod is ScubaVenture, which will throw a line out of place about every time the screen scrolls. The line is solid, which makes it more difficult or impossible for the player to pass it without losing a life. Mouser also shows some graphical garbage on the top of the screen with the Tandy mod, but it does not interfere with game play.
Memory Sidecars
If you are not fortunate enough to obtain a jrIDE, you can add memory expansions that were sold for the PCjr. if you can find one. These typically come with 128KB or more of RAM, and without any modifications you can add up to 512KB of RAM in this way to the system. IBM's Memory Expansion is configured through four dipswitches on the back of the sidecar. Only one switch should be "ON" for each Expansion, the rest must be OFF. You could attach up to four expansions, and the first expansion should have switch 1 ON, the second expansion switch 2 ON, the third expansion switch 3 ON and the fourth expansion switch 4 ON.
The IBM Memory Expansion can be modded to have 512KB on a single sidecar. You must remove the sixteen 64Kx1 DRAM chips and replace them with 256Kx1 DRAM chips. Just to the right of the large 74S409 chip, you will see three solder pads closely aligned in a row, with a trace connecting the left and center pads. You must cut that trace and connect the center and right pads. It may be possible to mod this card to 736KB, but I do not know how.
The IBM PCjr. Internal Modem fits in a special slot inside the PCjr. The Modem sits at COM1 and this is undoubtedly its most useful purpose in the modern era. The BIOS designates the internal serial port, with no modem installed, as COM1. The resources the serial port uses, I/O 278H and IRQ3, are those typically assigned to COM2. This causes programs no end of confusion, and usually a program like COMSWAP is used to redesignate the serial port as COM2.
The Internal Modem uses the resources typically assigned to COM1, I/O 3F8H and IRQ4. By installing one, even if you never intend to use it, the BIOS will assign the Modem to COM1 and the serial port to COM2.
If you want to use a serial mouse and you don't have the Internal Modem installed, you can use the Cutemouse v1.91 driver. You will need to use the following command line argument /S13. This tells the driver to use the device at COM1 and IRQ3.
IBM's PCjr. Internal Modem is based on the Novation 103 Smart Modem, which uses a command set somewhat different from the Hayes compatible command set most terminal emulator programs expect. However, once you learn the basic commands and how to implement them in a terminal emulator, it can be used, as it was intended, at 300 baud. It does not have any speaker on it, so the only way to know whether you have connected is to review the messages sent from the modem. All commands can be shortened to the first letter, like the Hayes command set in many instances.
To initialize the modem, use the command : I
To set the format, use the command : F. The modem supports the following serial data formats (data bits:parity:stop bit) :
0 - 7:M-1
1 - 7-S-1
2 - 7-O-1
3 - 7-E-1
4 - 8-N-1
The default is 7-E-1. M is Mark Parity, S is Space Parity, E is even Parity and O is Odd Parity. To set the format to 8-N-1, use the command : F 4. The initialize and format commands can be carried on the same command line, separated by a comma. Using an 8-bit speed will show more corrupt characters than using the 7-bit speed, but it is faster and more compatible with BBS terminals that still allow for dialup.
The command to answer is : A. The hangup command is : H.
Any commands to the modem must be prefaced by a control character. The default character is 0E/Ctrl N. This is the equivalent of the AT control character of the Hayes commands. The command string must be terminated by a carriage return/Ctrl M, just like Hayes. However, there is no +++ equivalent, the modem will always view one of the 255 ASCII codes as a command code, but it does allow you to change the default ASCII value with the N command.
The program ProComm, 2.4.3, which was very popular back in the day, will work with the PCjr. Internal Modem. The default strings to enter in the setup menu look like these :
^N I, F 4 ^M
^N D w##########
^M
^N H ^M
If you have a phone service that uses a stuttering dial tone to indicate that you have new voicemail, this modem may interpret the stuttering signal as a BUSY signal and do nothing. Clear your voicemail.
Many of the few BBSes expect a faster transmission rate than 300 baud or a more robust modem solution. One BBS that more or less works is the Capitol City Online BBS out of Frankfort, KY. Its telephone number is 502-875-8938.
IBM PCjr. Parallel Printer Attachment
This sidecar adds one parallel port and was a very popular add-on for the PCjr, which did not come with a parallel port. The parallel port is a standard DB-25F connector, unlike virtually every port on the back of the PCjr. It uses the standard CGA LPT1 resources, I/O 378H and IRQ7. If there is no parallel printer sidecar installed, then the serial port will receive the LPT1 designation. When the parallel port is installed, the BIOS will reassign LPT1 to it. IBM did not allow the settings on the parallel port adapter to be changed, so only one parallel port is supported. There is a fairly simple mod to change the I/O to the LPT2 278H address, you can find it here : http://www.brutman.com/PCjr/lpt2_mod.html
The parallel port is a unidirectional port by default, capable of nibble transfers. There is an easy mod to make the parallel port bidirectional. This will double throughput when an external devices wants to send data through the parallel port to the computer. The instructions for the mod can be found here : http://www.brutman.com/PCjr/parallel_port.html This mod will also work with the ISA-based IBM PC Printer Adapter and the IBM Monochrome Display and Printer Adapter and probably all clones that implement a parallel port strictly using TTL logic.
The parallel port is useful for more than just connecting to printers, although it can do that too. I have connected it to a 2008 vintage Brother MFC-8860DN and it was able to print from DOS. It is far more useful to use with a 100MB zip drive or an Ethernet adapter like the Xircom PE3-10BC. The Xircom's packet driver (PE3PD.COM) and test program (PE3TEST.EXE) work just fine with an 8088 machine and a PCjr. The packet driver is initialized as follows for a PCjr. with an unmodified parallel port :
pe3pd sint=60 non
The non tells the adapter to operate in the non-Bidirectional mode (a.k.a. Unidirectional), and sint=60 assigns the Packet Driver services to software interrupt 60H. The driver can autodetect the presence of the adapter on any of the LPT assignments and the Interrupt.
Using the Xircom adapter, you can transfer files to and from the PCjr. with relative ease. There is a suite of TCP/IP utilities called mTCP, which you can get from here. http://www.brutman.com/mTCP/ The DHCP client utility especially useful for automatically obtaining all the critical information (IP, Gateway, Nameserver) from your route to connect to the Internet. I typically start up the packet driver and dhcp client in a batch file which I created (MTCP.BAT) and it looks like this :
c:\mtcp\pe3pd sint=60 non
set MTCPCFG=c:\mtcp\tcp.cfg
c:\mtcp\dhcp.exe
There are other useful utilities. The IRCJR functions as a basic Internet Relay Chat client. You can use it to chat on IRC. It will not download files from IRC though. I use it to connect to the Vintage Computer IRC channel on irc.slashnet.org, /join #vc. SNTP will obtain the time and date from an internet server and set the time and date in DOS. This is very useful for systems without a Real Time Clock or you want more exact time. There is also a Telnet client with ANSI emulation for all your text-based terminal needs. There is also a basic FTP client. It can copy (get) multiple files, but not sub-directories.
To actually use these utilities, you need to create a file called TCP.CFG. At a minimum, the following is required :
PACKETINT 0x60
HOSTNAME PCjr
The PACKETINT must correspond with the Packet Driver's software interrupt, but the HOSTNAME can be anything. DHCP will add or change the necessary configuration every time you start the DHCP server. Individual mTCP utilities will have their own settings in this file.
The most important utility is the FTP Server. This utility lets you operate your PCjr. as an FTP Server. The practical application of this utility is an easy and modern method to send from and receive files to your PCjr.'s (or any DOS machine) drives. You setup the FTP Server on the PCjr,'s end and use a modern FTP Client on your modern PC like Filezilla. This is what I use, and with a few tweaks to Filezilla, it works well.
In Filezilla, set the transfer type to binary, the maximum number of connections to 1, the timeout to 200 seconds and the speed limits to 25K/25K. If you have a bidirectional port, you can push the speeds higher, but 50KB/50KB is the max you will probably be able to get from a PCjr. A V20 or faster CPU will speed up transfer rates a bit. Filezilla expects to talk to a modern machine, and it runs so fast that the flow control will get screwed up waiting for the slow PCjr.
On the PCjr. FTP Server, I recommend the following lines added to TCP.CFG :
FTPSRV_PASSWORD_FILE ftppass.txt
FTPSRV_LOG_FILE log.txt
FTPSRV_EXCLUDE_DRIVES AB
FTPSRV_FILEBUFFER_SIZE 16
FTPSRV_TCPBUFFER_SIZE 16
FTPSRV_PACKETS_PER_POLL 10
The first two are required for FTP Server to run. The remainder give the maximum buffer sizes and exclude the floppy drives.
jrIDE
jrIDE is an amazing sidecar that was recently (2012) developed by PCjr. enthusiasts, mainly Alan Hightower. It combines 1MB of SRAM, a real time clock chip and can boot 16-bit IDE drives. It can support an IDE master and an IDE slave drive, and it can effectively support hard drives up to 8GB (the maximum of using DOS and FAT16).
The RTC is a Dallas 12887 module, and is socketed for replacement. The date and time is set by a program called rtc, loaded in the autoexec.bat file on startup. IRQ 1, 2 or 7 can be selected for its operation. I suggest IRQ2 because the parallel port uses IRQ7 and the keyboard on a regular PC uses IRQ1, which could possibly confuse some programs that are not PCjr-aware. The Speech Attachment also uses IRQ1. Using an IRQ really is not essential for this function.
In order to set the date and time, you will need a small program called rtc.com, available here:
http://www.retrotronics.org/svn/jride/trunk/prebuilt/jr/
To set the date and time for the RTC, first, set the correct date and time in DOS using the DATE and TIME commands. Next, run the rtc.com program with the /r switch. This will send the date and time you told DOS to the RTC. Finally, add the rtc.com program to your autoexec.bat file with the /d switch. Upon every bootup, this will fetch the correct date and time from the RTC and automatically set it in DOS.
The IDE header is at a right angle and has all 40 pins. Pins 1 and 2 are at the bottom of the board. The key pin can (via jumper) be used to provide +5v to power low-power devices like Disk On Module (DOM) devices or Compact Flash cards. The PCjr., without a power sidecar, is not likely able to supply sufficient power for a 2.5" or 3.5" hard disk drive. I found that even a DOM had difficulty when it was the third card in the system.
The jrIDE BIOS is based on the Universal XT-IDE BIOS, so it should be able to support drives up to 8.4GB in size supported by Int 13 and maybe higher if true LBA is used.. Practically speaking, the use of DOS (pre 7.1) is going to limit you to 4GB drives. You will need PC-DOS or MS-DOS 4.0 or better to use a primary partition (primary drive) greater than 32MB and logical drives greater than 32MB. With DOS 4.0 or above, you can have a primary partition of 2GB (C:) and one or more logical drives in the extended partition within the remaining 2GB (D:). With DOS 3.3, below, you will be limited at a maximum to a primary 32MB partition (C:) and 32MB logical drives in the extended partition, D:-Z: for 736MB total hard disk space. With PC-DOS 3.0-3.2, only one DOS 32MB partition is available for a C: drive per disk. DOS 2.1 allows only one 15MB partition for C:. Using DOS 5.0 or above requires patching the DOS system files as outlined here : http://www.brutman.com/forums/viewtopic.php?f=3&t=224&p=1978&hilit=stacks#p1978
Of that 1MB of RAM, you can have 736KB total conventional memory, even though the PCjr. only counts to 640KB on the startup screen. However, without a device driver loaded in config.sys, DOS will only see 128KB of RAM, and that is before it loads itself and the video buffer is taken into account. The remaining RAM is the slow RAM controlled by the video controller.
The device driver to use with the PCjr. and jrIDE is JRCONFIG.SYS v3.10 from PC Enterprises. The most basic use of it is to load it in config.sys like so :
DEVICE=C:\JRCONFIG.SYS -V64
When this driver is loaded with a jrIDE, it will give you 608KB of conventional memory free. Physically, this memory is between the first, slow 128KB and the video buffer window which starts at 736KB. The lower 128KB is reserved for DOS and the video memory. You can use what is left over for a RAM disk. RAM disks are especially important if you are using a null-modem to transfer data to or from a PCjr. because the machine lacks DMA.
A system booted to DOS with JRCONFIG v3.10 and no other drivers or an autoexec.bat loaded will report 753,664 total bytes (736KB) and 610,656 bytes free (596KB). You can also try an earlier version of the driver called JRCONFIG.DSK v2.14, which should require less RAM.
The driver has many command line switches, the only one that most people will need is -v64. This will allocate 64KB of video memory within a 32KB video page so that programs using the 320x200x16 and 640x200x4 modes will work.
The only major downside to using JRCONFIG is that it is not really compatible with Cartridge BASIC. REM out the line with JRCONFIG or simply rename config.sys when you need to use Cartridge BASIC and DOS. Cartridge BASIC is limited to 64KB free memory and freaks out if it is told there is more than 128KB in the system.
Since JRCONFIG uses software interrupt 60, which is the default software interrupt for many Ethernet DOS packet drivers, assign the packet driver to use a different interrupt.
You can find JRCONFIG here : http://www.brutman.com/PCjr/pcjr_downloads.html jrconfig.zip is the v2.14 version, jrcfg310.zip is the v3.10 version.
To obtain a jrIDE, join the PCjr. Web Forum, here : http://www.brutman.com/forums/ Be prepared to spend well over $100 to obtain an assembled one, and you may have to wait. The board assembly itself requires only through hole soldering, but the project is still quite the undertaking.
NEC V20
Most IBM PCjr. will have a socketed 8088 CPU, located underneath the disk drive. If you are unlucky and received one of the last units sold by IBM, the CPU will be soldered onto the motherboard. You can remove the 8088 CPU from the socket and replace it with a V20 CPU for a decent (10-15%) speed boost while retaining nearly 100% compatibility with software. The most common part number for the V20 is the NEC D70108. If you have a soldered CPU, you can always remove the CPU and solder in a 40-pin socket.
The V20, V30, 80186 and 80286 and later CPUs are not 100% compatible with 8086/8088 software because the 8086/8088 have undefined/illegal (as opposed to undocumented) opcodes whereas the later CPUs do not. The only game I am aware of, after a great deal of searching, that may not support the V20 PCjr. is Lode Runner, but every version of the game available for download works just fine with a V20. Every cartridge game for the PCjr. works fine with the V20.
Increasing the clock speed of the 8088 or V20 is not for the faint of heart. There is one 14.318MHz crystal on the PCjr that is used for all system timing. This includes the CPU clock speed, the 8253 Timer input and the OSC signal. In the PC it is arguably more difficult to overclock because the DMA chip uses the CPU CLK signal for its timing. Replace that crystal and all three frequencies, which are derived from an Intel 8284 Clock Generator chip, will change.
There is a PCB design called PC-SPRINT that essentially directs a higher clock solely to the CPU. It is a separate board which is piggybacked on the existing CPU socket. It has a separate crystal and a second 8284. Typically, speeds of 7.16MHz or 7.37MHz are stable, although some people have boasted of obtaining a 9.54MHz speed.
IBM PCjr. Speech Attachment
This sidecar contains a TMS5220 chip very similar to the chips used in the Speak & Spell toys of the time and sounds identical. It uses two methods to digitize and playback sound, LPC (linear predictive coding) and CVSD (continuously variable slope delta modulation). The TMS chip handles the LPC while the CVSD is handled by a MC3418. Interfacing to these chips is through an 8255 PPI and 8254 Timer. All audio output is routed through the system board multiplexer just like the 3-voice chip.
LPC allows for the use of compressed digitized samples and the sampling rate is of higher quality. The Sppech Attachment uses this method to play its built in vocabulary of 196 words, phrases and sound effects. Its 32K ROM chip resides at CE000-CFFFF. The voice playback of the vocabulary samples has an 8KHz sample rate. The built-in vocabulary is very easy to access in BASIC. You can add your own (compressed) vocabulary words with a computer that has a program that can encode the recorded sound into the format of the Speech Attachment.
CVSD allows for recording voice and sound through the microphone input and play it back. Normally voice recording is limited to disk size, but if you have a large hard disk, this will be less of a concern. The recording and playback speed through the microphone ranges from 1.8K-4.8K per second. CVSD encodes at 1 bit per sample, so that audio sampled at 38.4 kHz is encoded at 38.4 kbit/s. The default addresses used are FB98-FB9F, FF98 and FF9F. It also uses IRQ1.
The best program I have discovered to use the Speech Attachment is MAKETALK from PC Enterprises. It will allow you to play the vocabulary and build sentences for recording by an external device and also allow you to record and playback to the limits of your disk space.
IBM PC Compact Printer
IBM released this low-cost printer to go with its low cost entry system. It is a thermal printer and uses an 8-pin head. It has just one button for line feed and a power switch and LED. The printer uses the PCjr. serial BERG connector that plugs directly into the PCjr, but adapters exist that can convert it into a DB-25 connector for use with a regular serial port and a PC compatible.
This printer can print 56 characters per second, but only prints from left to right. It can print 80 characters per line in standard mode, and supports double width mode, compressed mode, compressed/double width mode and underlining. It prints all the 256 IBM ASCII and Extended ASCII characters except for the 64 block characters at 176-223. It also supports a 480-bit graphics mode.
The Compact Printer uses an 8.5" wide paper roll. The rolls typically are not perforated, so the user must cut or tear pages to length. The lack of perforations makes it ideal for banners and graphics. Staples and OfficeDepot sell 8.5" rolls, typically 98' or 164'. Thermal printers do not need ink ribbons, ink or toner cartridges, so their operational cost is strictly from the paper.
The printer has a data transfer rate of 1200bps and uses 1 start bit, 8 data bits, no parity and 2 stop bits. In order to obtain reliable operation, as in no missing or skipped characters, you should use the following parameters with the MODE command :
mode COM2: 1200, n, 8, 2, p
Without the IBM Parallel Printer Attachment, the BIOS assigns the serial port to LPT1. Thus devices printing only to LPT1 should not have a problem. If you have a Parallel Port attached, then it will be assigned to LPT1. You can redirect LPT1 to COM1 or COM2, depending on which your printer is designated, by the command :
mode LPT1:=COM1: or
mode LPT1:=COM2:
The last issue with this printer is loading the paper. First, you lift the smoky colored cover. Next, there is a tab on the left side that you push in, allowing the paper roll enough room to fit inside the housing. Fit the cardboard portion of the roll onto the two pegs. The end of the paper must be feeding upwards and counterclockwise. Release the latch on the side to let the printer allow the paper to be fed to the thermal head. Take the edge of the paper, fold it in a U shape, and guide it down behind the beige plastic bar. Use the paper feed button until the paper catches. Gently adjust the paper, once you can see it through the underside of the thermal element so that it is straight and then close the latch on the side to hold the paper in place. Make sure you have enough paper so that a little bit of paper appears over the plastic cover when you put it down.
Tandy Mod
One upgrade you may want to make to your system board is to make it more compatible with games that support the 160x200x16, 320x200x16 or 640x200x4 graphics modes only with a Tandy 1000. Some games (essentially just about every PC game released after 1985) will allow you to select Tandy graphics, but when you play these games on a stock PCjr., you will only see every other line. The Tandy mod will fix this problem. A good guide to the mod with instructions can be found here : http://vintagemashups.net/2011/12/ibm-pcjr-tandy-1000-graphics-mod/
Other problems may prevent a game from working on a PCjr., including when a game auto-detects a Tandy 1000, keyboard or joystick input issues, graphical anomalies due to the differences between the Tandy and PCjr. graphics controllers, disk-based copy protection failures. You may need to set the audio multiplexer to output 3-voice music before starting a game.
Of PCjr. games, the only game I know of that doesn't like the Tandy mod is ScubaVenture, which will throw a line out of place about every time the screen scrolls. The line is solid, which makes it more difficult or impossible for the player to pass it without losing a life. Mouser also shows some graphical garbage on the top of the screen with the Tandy mod, but it does not interfere with game play.
Memory Sidecars
If you are not fortunate enough to obtain a jrIDE, you can add memory expansions that were sold for the PCjr. if you can find one. These typically come with 128KB or more of RAM, and without any modifications you can add up to 512KB of RAM in this way to the system. IBM's Memory Expansion is configured through four dipswitches on the back of the sidecar. Only one switch should be "ON" for each Expansion, the rest must be OFF. You could attach up to four expansions, and the first expansion should have switch 1 ON, the second expansion switch 2 ON, the third expansion switch 3 ON and the fourth expansion switch 4 ON.
The IBM Memory Expansion can be modded to have 512KB on a single sidecar. You must remove the sixteen 64Kx1 DRAM chips and replace them with 256Kx1 DRAM chips. Just to the right of the large 74S409 chip, you will see three solder pads closely aligned in a row, with a trace connecting the left and center pads. You must cut that trace and connect the center and right pads. It may be possible to mod this card to 736KB, but I do not know how.
Sunday, March 2, 2014
A Hypothesis of the Tandy 1000 Parallel Ports
The Tandy 1000s, until the RL and TL/3, have a built in parallel port. It does not use a standard DB-25 parallel port connector. It uses a 34-pin card edge connector, and Tandy usually supplied adapter cables to connect to a Centronics 36-pin connector at the printer. However, there are some very useful devices that use the parallel port as a generic input and output port. Parallel port floppy drives, CD-ROMs, Zip drives, the Disney Sound Source and Network Adapters could in theory and with an adapter use these card edge ports. What is unknown is whether Tandy 1000 ports can support any kind of standardized (and I mean that loosely) data input. To begin the exploration of the Tandy parallel ports, first I will need to discuss a standard IBM PC printer port.
Unidirectional Printer Ports
The first parallel printer port for the IBM PC had eight data lines, five status lines and four control lines. The data lines allowed the computer to send eight bits of data to the printer. The four control bits would send control information to the printer, which could send five bits back to the PC on the status bits. Thus, the parallel port has three registers, and in a system without a monochrome display adapter parallel port, their addresses are these :
0378 - Data Port
0379 - Status Port
037A - Control Port
The status port is read only, and the data and control ports are read and write capable. If the data or control port is read, the computer will read the bits last sent to the port. IBM warned against a printer or other external device trying to use the parallel port to write data on the lines meant for the data or control ports. Thus these ports are designated as output only ports. Officially, a printer communicated to the computer through the use of the status port. This port is designated as an input only port.
The bit assignments for the status and control ports become important to the discussion below :
Strobe - The strobe signal is sent to the printer to alert it that there is valid data byte on the data output lines. This signal is active low and held for at least 0.5uS. AKA STB,
Ack - The acknowledge signal is sent from the printer to tell the computer that the printer has received the data byte and ready to accept more data. This line is tied to IRQ7 through the IRQ enable bit, Control Port C4. This signal is typically held low for 5uS. AKA ACKNLG, PACK
Busy - The busy signal is sent from the printer to tell the computer, when high, that it cannot process data at the present time. This is typically when the printer is busy processing data, printing data, when it is offline or has reported an error.
Paper Out - The out of paper signal is sent from the printer and, when high, tells the computer that the printer is out of paper. AKA End of Form, P. End, PE, PAEM, Out of Paper
Select Printer (Status Port) - The printer selected signal is sent from the printer to indicate to the PC that, when high, the printer considers itself selected and on-line. AKA Printer Selected, SLCT, SEL
Auto Linefeed XT - The auto linefeed signal is sent to the printer to tell it, when low, to advance the printer a line after a carriage return. AKA AUTO FEED XT, AF
Error - The error signal is sent from the printer to the computer to alert the computer of a fault at the printer's end. This is typically when the printer is offline, out of paper or has some error condition. AKA FAULT
Init - The initialize printer signal is sent to the printer to tell it to reset itself and clear its printer buffer. This signal must be held low for 50uS for it to be effective. AKA PRIME
Select-Input (Control Port) - The printer select signal is sent to the printer to tell it that, when low, it has been selected and should be ready to receive data. AKA SLCT IN, Select-In
One thing to note about these bits is that of the Control Port signals, the Strobe, Auto Linefeed and Select-In (Output) are all inverted as they are output from their register to the connector. Since these are active Low, you must set these bits High (1) to activate these signals. Also, the Busy signal, as it comes from the printer, is also inverted at the Status Port. Since Busy is active High, a Low (0) bit means the Printer is Busy.
Not all bits are used by all printers. Most printers have a dipswitch to set the printer to the Auto Linefeed mode, since this usually desired. It is hard to imagine today that a printer or typewriter would not automatically advance to the next line after pressing the Carriage Return/Enter key.
IBM's Graphics Printer, essentially the standard of the day, had a dipswitch to always set Select Printer (which from the printer's perspective it is an output line) to the active state.
C5 is used as an Interrupt Enable line. It is active High, so when a (1) is written to the bit, IRQ7 will be sent when the Ack signal becomes active. The intended use for this signal is that the printer program, when the IRQ was sent, would know without having to waste time polling the Status Port that it could send the next byte to the printer.
Nibble Mode
Before the introduction of the PS/2 Bidrectional Mode, the Nibble mode was the only compatible way to read data from an external device connected to the parallel port. The external device would drive its data onto the status port. The high four bits of the port would be the easiest to use, which in this case would be the Busy, Ack, Paper Out and Select bits. This would form a 4-bit nibble, and two nibbles would form a byte. As the Busy signal is inverted, code would need to consider that in obtaining the right data nibble.
The Status Port is a 5-bit port, and if read eight times could be reformed into five bytes by including the Error bit in the read.
PS/2 Bidirectional Mode
In 1987, IBM released the PS/2 and it boasted of a bidirectional parallel port mode that would allow an external device attached to the parallel port to send eight bits of data to the computer via the data port. TTL-based parallel ports for the IBM PC family, including IBM's, could easily be modified to do this. In this case, Control Port C5, when set (1), would change the data output port to a data input port. The default behavior was that C5 was not set (0). When in data input mode, a read on the data port will give the value sent by the external device. A write to the port would do nothing.
IBM's PS/2 and PS/1 family had more advanced bidirectional capabilities involving new registers outside the parallel port I/O space, but the basic functionality described in the previous paragraph is all that could be assumed on a regular PC compatible.
Tandy 1000
While there are the later EPP and ECP parallel ports, this post is primarily based on what the built-in ports of the Tandy 1000 are capable of, and none of them are capable of such advanced functionality.
Tandy 1000 printer ports are based off the pre-IBM Centronics standard and have some differences. Tandy marketed many, many printers, and they were designed to work with all its computer lines, including the TRS-80, the Color Computer and the Tandy 1000, 2000, 1200, 3000 & 4000. Early printers did not use all the control and status lines of the IBM parallel printer port. The two handshaking signals, strobe and ack, are the most important for any printer.
The Select signals are not used on Tandy printers. Auto Linefeed is not used by some Tandy printers, the Init signal is not used by all Tandy printers and they provide an active low as well as an active high Busy signal on two separate pins. Some Tandy printers also provide +5v on their Centronics connector at pin 18, you will want disconnect this pin at the DB-25 end of the cable if you use one of these printers. Fortunately, pin 18 is unconnected on standard Centronics 36-pin male to DB-25 male printer cables. Tandy Centronics connectors put Init, when used, at Pin 33, whereas it is on Pin 31 on IBM Centronics connectors. This is the functional difference between Tandy Type A and B Card-edge to Centronics cables and Type C and D DB-25 to Centronics cables.
The Tandy 1000/A/HD have a 40-pin Parallel Port Array IC, it differs slightly from the later Array used on the SX, HX, EX and TX. The technical reference implies that it is capable of bidirectional operation. One difference is that the Auto Linefeed signal is on pin 32 of the 1000/A/HD card edge. On later machines this signal is found on pin 27. The Tandy 1000/A/HD connector leaves pin 34 unconnected, but later Tandys connect it to +5v.
The EX, HX, SX and TX all share the same Parallel Port Array IC and their ports are wired identically. While the IC has a pin (16) for the Select-Input (Control Port) line, it is not connected to any of the lines on the card edge. Additionally, all five Status Port lines are connected from the card edge to the IC, so theoretically the port is capable of nibble transfers. However, the Select Printer (Status Port) line usually needs to be connected via jumper to the Array IC because Tandy's printers do not use it).
Also, in theory, you could connect the Select-Input (Control Port) to the card edge and then to a parallel device by a custom adapter. However, you would need a pullup resistor and a capacitor as the other lines have.
The TL and SL use the Jacksboro version of the PSSJ chip to implement a parallel port. This chips does not have a pin for the Select-Input (Control Port) line at all. Ditto for the TL/2, SL/2 and RL, even though they use the more advanced Bonanza PSSJ. The number of pins on either version of the chip are the same. Like the earlier devices, the Select Printer (Status Port) needs to be enabled via jumper. On the TL/2 and RL, there are no jumper standoffs, so the jumper pins will need to be shorted.
The TL/3, RLX and RSX use the Hensdale version of the PSSJ, which has more pins and have a regular, bidirectional DB-25 parallel port. The Select-Input (Control Port) and Select Printer (Status Port) lines are present on the connector.
Contructing a Converter Cable
Fortunately, the 34-pin card edge connector used by the Tandy was also used by 5.25" floppy drives. The Tandy printer card edge connector is not keyed while the floppy connectors usually are, so you will need to get an unkeyed connector or cut the plastic inside. A short ribbon cable and a DB-25 female port connector is all that is required. As you can see, the cable is very straightforward until IBM pin 15. Never connect the card edge pin 34 to anything on a DB-25 connector. Pins 14, 26 and 32 are often grounded or unconnected, you can use one of the unconnected pins you try to connect Select In (Output). Pins 2, 4, 6, 8, 10, 12, 16, 18, 20, 22, 24, 31 and 33 are connected to ground, but one Tandy ground wire for each DB-25 ground pin should be fine.
Covox Speech Thing & Disney Sound Source
The Disney Sound Source is an 8-bit D/A converter that is housed in a parallel port dongle and connected to a speaker. The circuitry inside the dongle is powered by a 9V battery in the speaker, and a 4-pin wire with an RJ-11 jack connects the dongle to the speaker. It does not require a bidirectional parallel port, but it does have a problem with the Tandy card edge port.
The problem is that the Sound Source, in addition to the eight data lines, uses the Ack, Init and Select-Input (Control Port) lines to control the D/A converter. As the card edge does not include the Select-Input (Control Port) line, the adapter will not work correctly in a Tandy. Disney indicated that with a special adapter, the Auto Linefeed line could be used instead, but this would require a small modification to the code needed to run the Sound Source.
The Covox Speech Thing is a simpler device that does not use anything other than the data port, which is connected to a purely-passive resistor network to an audio jack. The Tandy PSSJ DAC can emulate a Covox device using a program called Setdac, assuming the Covox-supporting program obeys DOS LPT address assignments.
Xircom PE3 Series Parallel Port Ethernet Adapters
Iomega Parallel Port Zip-100 Drives
MediaVision Audioport
Will only work with the ports in the TL3, RLX and RSX. It is possible it may work in a TX or older if the Select-Input (Control Port) line is brought to the connector.
Digital Joystick Adapters
The parallel port can be used as an adapter for simple, Atari-style digital joysticks. This requires the game have specific support for this method. Dyna Blaster is an example of a game that came with such an adapter. In this case, the adapter had two DE-9 ports for Atari joysticks. As you may recall from a prior post, there are many, many devices that are compatible with the Atari port. For a game released in 1992 like Dyna Blaster, the user could use a spare Sega Master System or Mega Drive (Genesis) controller.
The maker of the adapter generally would not assume that the user would know the type of parallel port he had (unidirectional, bidirectional, EPP or ECP) or its setting. Using the basic unidirectional port, five inputs bits are available on the status port. Coincidentally, the basic Atari CX-40 joystick has four directional contacts and one button. Each one can use one status bit to signal whether the directional or button has been pressed. More buttons cannot be supported in this manner without activating some kind of multiplexer in the joystick.
Each button and joystick position hovers over an open switch. The switch is closed when the user presses the joystick in a direction or the button down. One contact of each switch is connected to a separate wire on the cable, and the other half of every switch is connected to a common wire. Using one of the four control or eight data bits for the common wire, twelve joysticks could be controlled in this way. The joystick essentially becomes a loop connector.
The Atari joystick has no chips inside it, nor does a Sega Master System or Atari 7800 controller, but the Genesis, NES and SNES controllers all have a logic chip or two that requires +5v. Fortunately, the Tandy card edge provides +5v on pin 34 (except for the 1000/A/HD) Using a dedicated line is much easier on the port than trying to combine the power with parallel port data pins as the NES and SNES adapters used by SNESkey do.
Parallel to SCSI Adapters
I take no credit for this discovery, that goes to my friend Cloudschatze, but there does exist a parallel port to Shuttle SCSI adapter that apparently works with the Tandy card-edge port to transfer data in both directions. Shuttle made an adapter with a driver that will work in a pure bidirectional mode and overlook the lack of a Select-Input (Control Port) line, unlike other adapters. Therefore, with the card edge to DB-25 converter, the Shuttle adapter and a SCSI storage device, it is quite possible to get the parallel port to transfer data to the Tandy, at least the *X or better models.
LapLink Cable
It is quite possible to get the MS-DOS program Interlnk to work with the Tandy 1000s and their parallel ports, see here for details :
http://nerdlypleasures.blogspot.com/2014/09/tandy-1000s-and-interlnk-and-laplink.html
Unidirectional Printer Ports
The first parallel printer port for the IBM PC had eight data lines, five status lines and four control lines. The data lines allowed the computer to send eight bits of data to the printer. The four control bits would send control information to the printer, which could send five bits back to the PC on the status bits. Thus, the parallel port has three registers, and in a system without a monochrome display adapter parallel port, their addresses are these :
0378 - Data Port
0379 - Status Port
037A - Control Port
The status port is read only, and the data and control ports are read and write capable. If the data or control port is read, the computer will read the bits last sent to the port. IBM warned against a printer or other external device trying to use the parallel port to write data on the lines meant for the data or control ports. Thus these ports are designated as output only ports. Officially, a printer communicated to the computer through the use of the status port. This port is designated as an input only port.
The bit assignments for the status and control ports become important to the discussion below :
| Line Name | IBM Pin | Active Low | Direction | Function | Bit |
| Strobe | 1 | Yes | Out | Control Port 37A | C0 |
| Data 0 | 2 | No | Out | Data Port 378 | D0 |
| Data 1 | 3 | No | Out | Data Port 378 | D1 |
| Data 2 | 4 | No | Out | Data Port 378 | D2 |
| Data 3 | 5 | No | Out | Data Port 378 | D3 |
| Data 4 | 6 | No | Out | Data Port 378 | D4 |
| Data 5 | 7 | No | Out | Data Port 378 | D5 |
| Data 6 | 8 | No | Out | Data Port 378 | D6 |
| Data 7 | 9 | No | Out | Data Port 378 | D7 |
| Ack | 10 | Yes | In | Status Port 379 | S6 |
| Busy | 11 | No | In | Status Port 379 | S7 |
| Paper-Out | 12 | No | In | Status Port 379 | S5 |
| Select (Input) | 13 | No | In | Status Port 379 | S4 |
| Auto Linefeed XT | 14 | Yes | Out | Control Port 37A | C1 |
| Error | 15 | Yes | In | Status Port 379 | S3 |
| Init | 16 | Yes | Out | Control Port 37A | C2 |
| Select-In (Output) | 17 | Yes | Out | Control Port 37A | C3 |
| Ground | 18-25 |
Strobe - The strobe signal is sent to the printer to alert it that there is valid data byte on the data output lines. This signal is active low and held for at least 0.5uS. AKA STB,
Ack - The acknowledge signal is sent from the printer to tell the computer that the printer has received the data byte and ready to accept more data. This line is tied to IRQ7 through the IRQ enable bit, Control Port C4. This signal is typically held low for 5uS. AKA ACKNLG, PACK
Busy - The busy signal is sent from the printer to tell the computer, when high, that it cannot process data at the present time. This is typically when the printer is busy processing data, printing data, when it is offline or has reported an error.
Paper Out - The out of paper signal is sent from the printer and, when high, tells the computer that the printer is out of paper. AKA End of Form, P. End, PE, PAEM, Out of Paper
Select Printer (Status Port) - The printer selected signal is sent from the printer to indicate to the PC that, when high, the printer considers itself selected and on-line. AKA Printer Selected, SLCT, SEL
Auto Linefeed XT - The auto linefeed signal is sent to the printer to tell it, when low, to advance the printer a line after a carriage return. AKA AUTO FEED XT, AF
Error - The error signal is sent from the printer to the computer to alert the computer of a fault at the printer's end. This is typically when the printer is offline, out of paper or has some error condition. AKA FAULT
Init - The initialize printer signal is sent to the printer to tell it to reset itself and clear its printer buffer. This signal must be held low for 50uS for it to be effective. AKA PRIME
Select-Input (Control Port) - The printer select signal is sent to the printer to tell it that, when low, it has been selected and should be ready to receive data. AKA SLCT IN, Select-In
One thing to note about these bits is that of the Control Port signals, the Strobe, Auto Linefeed and Select-In (Output) are all inverted as they are output from their register to the connector. Since these are active Low, you must set these bits High (1) to activate these signals. Also, the Busy signal, as it comes from the printer, is also inverted at the Status Port. Since Busy is active High, a Low (0) bit means the Printer is Busy.
Not all bits are used by all printers. Most printers have a dipswitch to set the printer to the Auto Linefeed mode, since this usually desired. It is hard to imagine today that a printer or typewriter would not automatically advance to the next line after pressing the Carriage Return/Enter key.
IBM's Graphics Printer, essentially the standard of the day, had a dipswitch to always set Select Printer (which from the printer's perspective it is an output line) to the active state.
C5 is used as an Interrupt Enable line. It is active High, so when a (1) is written to the bit, IRQ7 will be sent when the Ack signal becomes active. The intended use for this signal is that the printer program, when the IRQ was sent, would know without having to waste time polling the Status Port that it could send the next byte to the printer.
Nibble Mode
Before the introduction of the PS/2 Bidrectional Mode, the Nibble mode was the only compatible way to read data from an external device connected to the parallel port. The external device would drive its data onto the status port. The high four bits of the port would be the easiest to use, which in this case would be the Busy, Ack, Paper Out and Select bits. This would form a 4-bit nibble, and two nibbles would form a byte. As the Busy signal is inverted, code would need to consider that in obtaining the right data nibble.
The Status Port is a 5-bit port, and if read eight times could be reformed into five bytes by including the Error bit in the read.
PS/2 Bidirectional Mode
In 1987, IBM released the PS/2 and it boasted of a bidirectional parallel port mode that would allow an external device attached to the parallel port to send eight bits of data to the computer via the data port. TTL-based parallel ports for the IBM PC family, including IBM's, could easily be modified to do this. In this case, Control Port C5, when set (1), would change the data output port to a data input port. The default behavior was that C5 was not set (0). When in data input mode, a read on the data port will give the value sent by the external device. A write to the port would do nothing.
IBM's PS/2 and PS/1 family had more advanced bidirectional capabilities involving new registers outside the parallel port I/O space, but the basic functionality described in the previous paragraph is all that could be assumed on a regular PC compatible.
Tandy 1000
While there are the later EPP and ECP parallel ports, this post is primarily based on what the built-in ports of the Tandy 1000 are capable of, and none of them are capable of such advanced functionality.
Tandy 1000 printer ports are based off the pre-IBM Centronics standard and have some differences. Tandy marketed many, many printers, and they were designed to work with all its computer lines, including the TRS-80, the Color Computer and the Tandy 1000, 2000, 1200, 3000 & 4000. Early printers did not use all the control and status lines of the IBM parallel printer port. The two handshaking signals, strobe and ack, are the most important for any printer.
The Select signals are not used on Tandy printers. Auto Linefeed is not used by some Tandy printers, the Init signal is not used by all Tandy printers and they provide an active low as well as an active high Busy signal on two separate pins. Some Tandy printers also provide +5v on their Centronics connector at pin 18, you will want disconnect this pin at the DB-25 end of the cable if you use one of these printers. Fortunately, pin 18 is unconnected on standard Centronics 36-pin male to DB-25 male printer cables. Tandy Centronics connectors put Init, when used, at Pin 33, whereas it is on Pin 31 on IBM Centronics connectors. This is the functional difference between Tandy Type A and B Card-edge to Centronics cables and Type C and D DB-25 to Centronics cables.
The Tandy 1000/A/HD have a 40-pin Parallel Port Array IC, it differs slightly from the later Array used on the SX, HX, EX and TX. The technical reference implies that it is capable of bidirectional operation. One difference is that the Auto Linefeed signal is on pin 32 of the 1000/A/HD card edge. On later machines this signal is found on pin 27. The Tandy 1000/A/HD connector leaves pin 34 unconnected, but later Tandys connect it to +5v.
The EX, HX, SX and TX all share the same Parallel Port Array IC and their ports are wired identically. While the IC has a pin (16) for the Select-Input (Control Port) line, it is not connected to any of the lines on the card edge. Additionally, all five Status Port lines are connected from the card edge to the IC, so theoretically the port is capable of nibble transfers. However, the Select Printer (Status Port) line usually needs to be connected via jumper to the Array IC because Tandy's printers do not use it).
Also, in theory, you could connect the Select-Input (Control Port) to the card edge and then to a parallel device by a custom adapter. However, you would need a pullup resistor and a capacitor as the other lines have.
The TL and SL use the Jacksboro version of the PSSJ chip to implement a parallel port. This chips does not have a pin for the Select-Input (Control Port) line at all. Ditto for the TL/2, SL/2 and RL, even though they use the more advanced Bonanza PSSJ. The number of pins on either version of the chip are the same. Like the earlier devices, the Select Printer (Status Port) needs to be enabled via jumper. On the TL/2 and RL, there are no jumper standoffs, so the jumper pins will need to be shorted.
The TL/3, RLX and RSX use the Hensdale version of the PSSJ, which has more pins and have a regular, bidirectional DB-25 parallel port. The Select-Input (Control Port) and Select Printer (Status Port) lines are present on the connector.
Contructing a Converter Cable
| Line Name | IBM Pin | Tandy Pin |
| Strobe | 1 | 1 |
| Data 0 | 2 | 3 |
| Data 1 | 3 | 5 |
| Data 2 | 4 | 7 |
| Data 3 | 5 | 9 |
| Data 4 | 6 | 11 |
| Data 5 | 7 | 13 |
| Data 6 | 8 | 15 |
| Data 7 | 9 | 17 |
| Ack | 10 | 19 |
| Busy | 11 | 21 |
| Paper-Out | 12 | 23 |
| Select Input | 13 | 25 |
| Linefeed | 14 | 32/27 |
| Error | 15 | 28 |
| Init | 16 | 30 |
| Select-In Output | 17 | |
| Ground | 18-25 | see below |
Fortunately, the 34-pin card edge connector used by the Tandy was also used by 5.25" floppy drives. The Tandy printer card edge connector is not keyed while the floppy connectors usually are, so you will need to get an unkeyed connector or cut the plastic inside. A short ribbon cable and a DB-25 female port connector is all that is required. As you can see, the cable is very straightforward until IBM pin 15. Never connect the card edge pin 34 to anything on a DB-25 connector. Pins 14, 26 and 32 are often grounded or unconnected, you can use one of the unconnected pins you try to connect Select In (Output). Pins 2, 4, 6, 8, 10, 12, 16, 18, 20, 22, 24, 31 and 33 are connected to ground, but one Tandy ground wire for each DB-25 ground pin should be fine.
Covox Speech Thing & Disney Sound Source
The Disney Sound Source is an 8-bit D/A converter that is housed in a parallel port dongle and connected to a speaker. The circuitry inside the dongle is powered by a 9V battery in the speaker, and a 4-pin wire with an RJ-11 jack connects the dongle to the speaker. It does not require a bidirectional parallel port, but it does have a problem with the Tandy card edge port.
The problem is that the Sound Source, in addition to the eight data lines, uses the Ack, Init and Select-Input (Control Port) lines to control the D/A converter. As the card edge does not include the Select-Input (Control Port) line, the adapter will not work correctly in a Tandy. Disney indicated that with a special adapter, the Auto Linefeed line could be used instead, but this would require a small modification to the code needed to run the Sound Source.
The Covox Speech Thing is a simpler device that does not use anything other than the data port, which is connected to a purely-passive resistor network to an audio jack. The Tandy PSSJ DAC can emulate a Covox device using a program called Setdac, assuming the Covox-supporting program obeys DOS LPT address assignments.
Xircom PE3 Series Parallel Port Ethernet Adapters
Iomega Parallel Port Zip-100 Drives
MediaVision Audioport
Will only work with the ports in the TL3, RLX and RSX. It is possible it may work in a TX or older if the Select-Input (Control Port) line is brought to the connector.
Digital Joystick Adapters
The parallel port can be used as an adapter for simple, Atari-style digital joysticks. This requires the game have specific support for this method. Dyna Blaster is an example of a game that came with such an adapter. In this case, the adapter had two DE-9 ports for Atari joysticks. As you may recall from a prior post, there are many, many devices that are compatible with the Atari port. For a game released in 1992 like Dyna Blaster, the user could use a spare Sega Master System or Mega Drive (Genesis) controller.
The maker of the adapter generally would not assume that the user would know the type of parallel port he had (unidirectional, bidirectional, EPP or ECP) or its setting. Using the basic unidirectional port, five inputs bits are available on the status port. Coincidentally, the basic Atari CX-40 joystick has four directional contacts and one button. Each one can use one status bit to signal whether the directional or button has been pressed. More buttons cannot be supported in this manner without activating some kind of multiplexer in the joystick.
Each button and joystick position hovers over an open switch. The switch is closed when the user presses the joystick in a direction or the button down. One contact of each switch is connected to a separate wire on the cable, and the other half of every switch is connected to a common wire. Using one of the four control or eight data bits for the common wire, twelve joysticks could be controlled in this way. The joystick essentially becomes a loop connector.
The Atari joystick has no chips inside it, nor does a Sega Master System or Atari 7800 controller, but the Genesis, NES and SNES controllers all have a logic chip or two that requires +5v. Fortunately, the Tandy card edge provides +5v on pin 34 (except for the 1000/A/HD) Using a dedicated line is much easier on the port than trying to combine the power with parallel port data pins as the NES and SNES adapters used by SNESkey do.
Parallel to SCSI Adapters
I take no credit for this discovery, that goes to my friend Cloudschatze, but there does exist a parallel port to Shuttle SCSI adapter that apparently works with the Tandy card-edge port to transfer data in both directions. Shuttle made an adapter with a driver that will work in a pure bidirectional mode and overlook the lack of a Select-Input (Control Port) line, unlike other adapters. Therefore, with the card edge to DB-25 converter, the Shuttle adapter and a SCSI storage device, it is quite possible to get the parallel port to transfer data to the Tandy, at least the *X or better models.
LapLink Cable
It is quite possible to get the MS-DOS program Interlnk to work with the Tandy 1000s and their parallel ports, see here for details :
http://nerdlypleasures.blogspot.com/2014/09/tandy-1000s-and-interlnk-and-laplink.html
Saturday, March 1, 2014
Evolution of 8088 PCs
From the first IBM PCs, there was a steady stream of innovation and improvements to PC compatible computers using an 8088 CPU. However, there were also some bumps along the way. In this entry, I will try to identify many of the positive and negative features of the main 8088 members of the IBM PC and Tandy 1000 families.
1. IBM PC Model 5150 First Version
Revised Expansion Card Brackets - Early PC brackets are black and color and are wider than later silver brackets. This can be a problem using cards side by side in later systems.
Dual Floppy Drives - 2x360KB Floppy drives on Model 25-1051 and 1054, boot floppy can be selected on bootup.
1. IBM PC Model 5150 First Version
IBM PC BIOS 1st & 2nd Revision - The original PC BIOS was the byword for compatibility.
Chassis - two full height drive bays, unique system board mounting, 13" maximum expansion board length, PC cone speaker.
System Board & Expansion Cards - Use of off the shelf components or TTL logic chips, configuration by two rows of dipswitches.
Power Supply - The form factor would be the same for the IBM PC/XT and this established a standard "AT Power Connector", passthrough port for monochrome monitor
Expansion Slots - The 8-bit PC or XT slot was introduced. Five slots were better than most other home computers at the time. However, the floppy disk controller, the video card and memory cards each took up a slot, so expansion was limited.
Cassette Interface - Important for saving programs in Cassette BASIC, used in Music Construction Set. 5-pin DIN connector, used TRS-80 cassette cables
Diskette Drive Adapter - Standard equipment, supports all double density drives, 34-pin card edge connector.
Diskette Drive (Single Sided) - Tandon TM100-1s were used in the beginning, supporting 160KB or 180KB per side. 4-pin molex connector used.
System Board Memory - 16-64KB on the motherboard, 16KB minimum, expandable to 544KB via expansion slot memory upgrades, first bank soldered, remaining three banks socketed.
System ROM - 6 x 8KB sockets, five used for BASIC and BIOS. Empty socket, but requires an adapter for EPROMs.
IBM PC-DOS 1.0 - Included Disk BASIC and Advanced BASIC, loads COMMAND.COM, IBMIO.COM and IBMDOS.COM.
Asychronous Communications Adapter - 8250B UART serial port, switchable between COM1 and COM2, DB-25 male connector. Most can work in XT Slot 8.
Printer Adapter - Printer port, 378H (or 278H with modification), DB-25 connector female connector
Game Control Adapter - DA-15 female connector, joystick support (third party), four axes and four buttons.
Monochrome Display and Printer Adapter - DE-9 female display connector, 80-column text, 9x14 character cell, TTL monochrome displays only
IBM PC Display Model 5151 - Display for the above adapter and later Hercules Graphics Card, powered through PC power supply, long persistence phosphor, monochrome green screen, brightness and contrast controls.
Color/Graphics Adapter - CGA, 16 colors selectable, 4-color palettes, 40 & 80 column text mode, composite color output, artifact color, 320x200 and 640x200 graphics modes, RCA composite video jack, light pen support, RF switchbox (third party) support
Math Coprocessor - Unidentified at first, empty 40-pin socket for 8087 upgrade.
IBM PC Keyboard - 83-key first standard keyboard, Function keys on side, buckling spring technology, 5-pin DIN connector
IBM Graphics Printer Model 5152 - Epson MX-80 clone, parallel printer, dot matrix printer
2. IBM PC Second Version
IBM PC BIOS 3rd Revision - Fixed bugs, added support for 640KB of memory, bootable option ROMs
IBM PC-DOS 1.1 - Double sided disk drive support, used Tandon TM100-2As.
Double sided disk drives - 320K and 360K per disk supported
System Board Memory - 64KB to 256KB on system board, now expandable to 640KB via expansion slot upgrades
Bootable ROM - Devices can have a boot ROM and the BIOS will allow the device to install its own boot handler, booting directly to a hard drive now possible. EGA and VGA support possible.
3. IBM PC/XT Model 5160
System Board - Configuration now only by one bank of dipswitches. Memory autodetected, tested and counted at bootup. Faster bootup compared with PC.
Cassette Interface - Eliminated, making Cassette BASIC vestigial for programs that require it
IBM PC Color Display Model 5153 - Official CGA monitor (.31 dot pitch), 16 color support (intensity bit not properly supported on some third party monitors), color #6 brown, 14/13" viewable screen, vertical hold and size controls.
IBM Expansion Unit Model 5161 - Adds seven more ISA slots, and official method to add hard disk drive to PC (whose power supply was not considered to output sufficient power to supply hard drive requirements)
IBM Graphics Printer Model 2 - Printer capable of supporting all IBM Extended ASCII characters. Earlier printer did not.
Expansion Slots - Standard 8 expansion slots, distance between slots standardized for what would become known as ISA slots. Slot 8 is on custom bus and only works with special cards (like the Async card). Only 6 slots can support full length cards due to the case.
Revised Expansion Card Brackets - Early PC brackets are black and color and are wider than later silver brackets. This can be a problem using cards side by side in later systems.
Power Supply - 130W, sufficient to support a hard drive and more
Fixed Disk Adapter - Built around Xebec chips, standardized XT hard drive controllers, including XT-IDE drives, supports two MFM drives, slow 6:1 interleave.
Fixed Disk - 10MB Seagate ST-412, Cylinder/Head/Sector addressing, MFM, Full Height.
System Board Memory - Same four banks as IBM PC, but all four banks socketed
IBM PC-DOS 2.0 - 9 sector floppy disks supported for 180KB per side or 360KB per disk, device driver support, revised file handling system, hard disk support (15MB maximum)
ROM Sockets - Support Standard 32KB EPROMS for 64KB ROM (only 40KB used on XT first BIOS)
Secret Memory Expansion - By adding a 74LS158 chip to socket U84, jumpering E2 and replacing the 64Kx1 RAM chips in banks 0 and 1 with 256Kx1 chips, you can have 640KB on the motherboard. Later XTs come with the mod.
Secret Memory Expansion - By adding a 74LS158 chip to socket U84, jumpering E2 and replacing the 64Kx1 RAM chips in banks 0 and 1 with 256Kx1 chips, you can have 640KB on the motherboard. Later XTs come with the mod.
4. IBM PC Portable
Composite Monochrome Monitor - 5" amber screen, composite connection to CGA card
Half-Height Diskette Drive - Two supported
Portability - For 1983, this meant a sturdy handle, a slightly modified keyboard that could attach to the chassis, and a power plug. System weighed almost 40 pounds. Only two full length cards supported
5. IBM PCjr. Model 4860
Cartridge Slots - For games and software, up to 64KB for each cartridge, two supported. Also used for Cartridge BASIC. Only appears on PCjr. and JX.
Sidecar Expansion Bus - Attach expansion boards without having to open computer, including parallel port and memory expansions. It lengthens the physical footprint of the system.
Cordless Keyboard - IR keyboard powered by 4xAA batteries and allowing for cordless operation 20-feet away, line of sight must be maintained, keyboard cord optional.
Internal Modem - 300 baud Novation non-Hayes compatible modem. Special internal slot connector, standard RJ-45 port.
System Board Memory - 64KB on motherboard, 64KB via internal expansion card, up to 736KB total via sidecar. System designed for 128KB, program must support extra RAM (Flight Simulator 2.0) or DOS must have a device driver to load more RAM
Enhanced CGA - Adds 160x200x16, 320x200x16 and 640x200x4 modes, but only BIOS level CGA compatibility
IBM PCjr. 3-Voice Sound - 3 square wave channels plus noise, 11-bit frequency selection, 4-bit volume control per channel, periodic and white noise selectable at four frequencies. Requires external speaker of some kind
System Configuration - Totally jumperless and dipswitchless, internal expansion cards and external IBM expansions automatically detected, memory detected (up to 640KB) and configured via software
Diskette Drive Controller - Only one drive supported, accessed at different ports, uses 34-pin header
Proprietary Expansion - External ports use unique BERG connectors.
Cassette Interface - Last PC compatible system to include a cassette interface. Only official IBM cassette cable is for the PCjr.
TV Connector - Only official IBM RF switchbox is for the PCjr.
Joysticks - Gameport on systemboard, supports two joysticks without a y-adapter. Only official IBM Joystick of the PC line is for the PCjr. Joysticks function the same as PC joysticks, just have a different connector.
Serial Port - Includes 8250B Serial Port, official IBM DB-25 adapter available. Uses COM2 resources, 278H/03I, but BIOS calls it COM1 if internal modem is not installed.
Joysticks - Gameport on systemboard, supports two joysticks without a y-adapter. Only official IBM Joystick of the PC line is for the PCjr. Joysticks function the same as PC joysticks, just have a different connector.
Serial Port - Includes 8250B Serial Port, official IBM DB-25 adapter available. Uses COM2 resources, 278H/03I, but BIOS calls it COM1 if internal modem is not installed.
Power & Cooling - 33W power card came first, followed by 45W card. 45W sufficient to power three sidecars. Only system here able to be run silently without risking overheating the power supply since the fan cools the disk inside the disk drive.
IBM PCjr. Color Display Model 4863 - Higher dot pitch (.42) than the PC Color Display, but also includes a speaker and uses the PCjr. video connector.
IBM Compact Printer - IBM's official serial printer, uses PCjr. serial connector, can use an adapter for any serial port, low cost thermal printer, surprisingly decent.
IBM PCjr. Speech Attachment - IBM's implementation of TI's Speak and Spell technology and more. Built in vocabulary. Capable of recording and playback of digitized sound. Later emulated by many devices.
Compatibility - Compatible with most IBM software, but notable exceptions include Microsoft Decathalon, 101 Monochrome Mazes and Microsoft Flight Simulator 1.x. Usually not so compatible with 3rd party software not written to take the PCjr. into consideration.
IBM PC-DOS 2.1 - Adds full BASIC support for PCjr's advanced graphics and sound, but requires Cartridge BASIC to work at all.
6. Tandy 1000 Model 25-1000
Expansion Slots - 3 standard XT slots, but only 10" cards or shorter supported
PCjr. Features - Brought over the Enhanced CGA and 3-Voice sound from the PCjr.
Compatibility Improvements - Unlike the PCjr., the Tandy 1000 could run most PC software that accessed the hardware directly.
Tandy 1000 Keyboard - 90 keys, including separate cursor keys and F11 and F12 keys, but support for these keys was hit or miss.
DMA & Memory Upgrades - Upgradeable to 384KB and DMA with one Board, 640KB with a second board. Full DMA support compared to PCjr (which only allowed DMA for floppy, and available via 3rd party upgrades only)
Printer Port - Built in, but limited and uses card edge connector
Power Supply - 54W, considered adequate for two drives and three expansion cards
Tandy CM-2 High Resolution RGBI Color Monitor - Later known as the CM-10 and CM-11, this was the Tandy equilavent of the IBM PC Color Display, although the dot pitch (.43) is not quite as sharp as IBM's (.31)
Tandy MS-DOS 2.11 - GW-BASIC supports enhanced graphics and sound of the Tandy 1000s, no FDISK to partition hard drive.
7. Tandy 1000A Model 25-1000A
Coprocessor - Adds 8087 Math Coprocessor Support
286 Express Upgrade - Compatible without special daughter board the plain 1000 requires.
286 Express Upgrade - Compatible without special daughter board the plain 1000 requires.
8. Tandy 1000HD Model 25-1000HD
Fixed Disk Drive - 10MB half-height model and Xebec controller that could use IRQ2. IRQ5 is standard on XTs, but the Tandy uses it for a vertical retrace interrupt.
DMA & Memory - Came with one board that gave DMA and allowed you to upgrade to 640KB with one board, also supplied a PLUS connector (see below) to add another expansion device like a serial card without taking up another slot.
Tandy CM-4 RGBI Color Monitor - Low cost RGBI monitor with a large dot pitch (.62). Not recommended for 640x200 graphics.
9. IBM PC/XT Revised
101-Key Keyboard - IBM made Model M keyboards work quite reliably on an XT with 2nd and 3rd BIOS. On a first BIOS XT or any PC, the odds are much lower that it will work at all.
Improved Drive Support - BIOS support in 2nd and 3rd BIOS for 3.5" double density and 5.25" high density drives, but a third party floppy controller is required for the latter.
System Board Memory - Supports 640KB on the motherboard without modification.
Mounting Hardware - IBM supplied late XTs in a dual half-height floppy configuration and included mounting hardware to fit them inside a full height bay.
10. IBM PC Convertible Model 5140
LCD Display - Simulates something like a 2-color CGA display, but in 320x200 (stretched to double width) can manage four intensities of color. Also can emulate the MDA.
Diskette Drives - IBM's introduction of 3.5" double density disk drives. Would take until the PS/2 for 3.5" disks to fully catch on.
Keyboard - 78 key keyboard, functions similar to PCjr. keyboard but improved by using IRQ1 for keyboard interrupt and not using CPU to deserialize scancodes.
Internal Modem - Slot inside for 1200 baud version of PCjr. modem, may or may not be Hayes compatible.
Expansion Bus - XT bus with multiplexed address and data lines.
Battery Operation - Uses CMOS 8088 CPU, SRAM to save power and allow for battery operation, system can be suspended indefinitely.
Attachable Printer - Thermal printer, more advanced than PC Compact Printer.
Display Slice - Provides full CGA compatibility to external RGBI monitor. Connector supports IBM PCjr. Display or IBM PC Convertible Color Display Model 5145. RCA jack can be used with color composite monitor. IBM also introduced the 9" IBM PC Convertible Monochrome Display with green phosphor.
Portability - Although still large and bulky by modern standards, this is a true laptop.
Convertibility - Can remove LCD to place unit underneath standalone monitor.
Convertibility - Can remove LCD to place unit underneath standalone monitor.
11. Tandy 1000 EX Model 25-1050
Dual Speed CPU - 7.16MHz/4.77MHz, selectable at bootup or via Tandy MS-DOS Mode command.
Slimline - Takes up less desk space and the keyboard is built into the system unit just like an Apple IIc. (Does not apply to SX)
Selectable Boot Drive - You could boot to the internal 5.25" floppy drive on an external 3.5" floppy drive
Expansion Bus - Uses a 62-pin version of the XT expansion bus, cards (called PLUS cards) stack onto each other, but must be short. (Does not apply to SX)
DMA and RAM Expansion - One PLUS card upgrades system to DMA and allows for 640KB
DMA and RAM Expansion - One PLUS card upgrades system to DMA and allows for 640KB
External Drive Connector - For connecting a second 5.25" floppy drive or a 3.5" floppy drive
Earphone Connector and Volume control - When you want a quiet PC (not on SX)
Earphone Connector and Volume control - When you want a quiet PC (not on SX)
12. Tandy 1000 SX Model 25-1051, 1052, 1054
Dual Floppy Drives - 2x360KB Floppy drives on Model 25-1051 and 1054, boot floppy can be selected on bootup.
Expansion Slots - Five expansion slots provided without any need for memory expansion
Memory Expansion - Upgrade from 384KB to 640KB with 8 x 256Kx1 chips
DMA - Included on all machines (optional on EX and HX)
Memory Expansion - Upgrade from 384KB to 640KB with 8 x 256Kx1 chips
DMA - Included on all machines (optional on EX and HX)
286 Express - Official 286 speed upgrade, 8KB cache that can be disabled, supports 80287 coprocessor. Software controlled. 8088 still available for programs that will not run on a 286 or on the faster speed
Tandy MS-DOS 3.2 - Supports 3.5" drives, FDISK partitioning, 3 extra 32MB DOS partitions using MLPART (non-standard)
Power Supply - 65W, considered adequate for two drives and five expansion cards
Power Supply - 65W, considered adequate for two drives and five expansion cards
13. Tandy 1000 HX Model 25-1053 (all the EX features plus) :
Boot Speed and Menu - Nearly instant boot to an optional menu where you can select the boot device (floppy, DOS, Deskmate)
EEPROM - Save settings permanently without dipswitches or jumpers.
DOS-in-ROM - Enough DOS 2.11 is on the system that you will not usually need to insert a DOS disk when loading programs off floppies. Disabled if a hard drive is installed. Also supports 3.5" disk drives natively, which regular DOS 2.11 cannot.
Power-in-drive cable - No separate molex or mini-molex connector required. A headache for wanting to use standard drives.
IBM PCjr. Exclusive Games - ScubaVenture & Mouser
The IBM PCjr. had eight cartridge games, and of them, two are exclusive to the system. They don't exist for anything other than a PCjr. and since they came on cartridges, they are not designed to work with any other computer. These games are ScubaVenture and Mouser.
ScubaVenture and Mouser, both programmed by Nasir Gebelli, are very minimalist, enigmatic games. As Gebelli only had 8,192 bytes to fit the program in (they use 8KB cartridges), you can understand why they lack anything beyond the minimum necessary to make playable games.
Gebelli himself is something of an enigma, as he began programming games for the Apple II, then he did these PCjr. games and some years later worked for Square in Japan programming Rad Racer, Final Fantasy 1-3 and Secret of Mana. Thereafter, he quit video games altogether and has not returned to them, despite his obvious talents.
Gebelli's PCjr. games lack polish, which is very unusual as IBM released them and shipped them on expensive cartridges. ScubaVenture has some very impressive smooth vertical scrolling and supports two player simultaneous play. Mouser is more of a puzzle game requiring a fair bit of strategy. Both use the PCjr.'s 160x200x16c mode for colorful low resolution graphics and 3-voice sound.
Common Controls
Press F1 for one player and F2 for two player (That is Fn and 1 or 2 on the PCjr. keyboard). If left untouched, the programs will enter a demo mode. Both games use the keyboard by default. They can use joysticks by pressing the J key on the keyboard. You can return to the keyboard by pressing the K key on the keyboard. Press Esc to pause. Each uses the cursor control keys and the spacebar or the joystick positions and button 1 on the joystick. When your game is over, you will not be returned to the title screen, so press F1 or F2 to start a new game.
ScubaVenture
The object of ScubaVenture is to collect treasures while swimming to avoid the eel on the bottom of the screen. If you touch the eel, you are stuck on the bottom of the screen. Press spacebar/button1 to launch a new diver. Once your third diver is eaten, the game is over.
You will come across yellow keys, each looking different. Touch the key to take it, and if you touch another key, you will take that. Soon you will see some "treasure boxes", and each corresponds to the shape of one key. If you touch the box with the right key, you will earn points. You will also earn points if you touch the red fish. Obstacles include seaweed, seahorses and the yellow "walls" on the sides of the screen. If you touch one of these obstacles, you will not be able to move forward and must try to find a way to move around or you will be eaten by the eel. In the one player game, a white diver will randomly swim across the screen and can block you and can take fish. He can swim through the yellow walls and the eel will not eat him.
In the two player game, each player will have three divers and compete on points. If you are using the keyboard, player one will use the regular keys and player two will use the AWSZ to move Left, Up, Right and Down. The Tab key will release another diver for player two. Player one's divers wear a green suit, player two's divers wear a red suit. When one player loses all of his divers, his diver will turn white and move randomly, just like the one player game.
Starting the game is a bit confusing. When you press F1 or F2, the title screen will seem to reset itself. If you keep pressing F1 or F2, the title screen will continue to reset. Let the music play until the ScubaVenture and NASIR text begin to flash. When that is finished, the game will start.
Mouser
The object of Mouser is to trap all the mice in each of the nine rooms. In each room there are walls that you can push clockwise or counterclockwise. The nine rooms are laid out in a 3x3 arrangement, and you can exit the rooms using the passages indicated. Each room is laid out in a 9x5 grid.
To trap a mouse, you must box it in on all four sides by walls. You cannot leave it any space to move. If you trap a mouse, the cat will eat it when you leave the screen. The cats are useless otherwise. If the mouse can move a square, then he isn't trapped. If one of the sides of the trap is the cat, the mouse will not be eaten when you leave the screen and you can't win the game. If you trap a mouse, a special sound will be heard and you will receive the points for trapping a mouse. Sometimes you will enter a screen and the mouse will already be trapped and you earn the points automatically. The time will also be reset.
To push a wall clockwise around a pivot, walk into it. To push a wall counterclockwise, push the spacebar/button 1 as you walk into it. The wall will turn 90 degrees on the pivot, and you can use the directions to move the walls to where you need them in the room. If you push one wall onto another, the wall will turn white and the next time you push that wall, one of the walls will be pushed forward in that direction one space. You cannot push a wall if it would go through a space occupied by a mouse, a cat, the cheese or a wall. Nor can you push a white wall onto a white wall. Sometimes when pushing a wall, there is some residue of it left behind, enough to block your character from that direction, but the mice can chew their way through it.
In some rooms, there are pieces of cheese. If a male (light red) mouse touches the cheese, he will eat it and the cheese will appear elsewhere on the screen. If a female (light magenta) mouse eats the cheese, it will spawn another male mouse. Male mice are stupid and walk back and forth in a pattern, but female mice can walk in a much less restricted fashion and are more likely to chase the player.
Some rooms are dark and require a flashlight to illuminate. You can find a flashlight in one of the rooms. The flashlight will only illuminate a circular space around the character, but as you enter and leave the room you can see the full layout for a second.
Two players alternate in trying to clear their rooms. If the player touches a mouse or runs out of time, he loses a life. Each player has three lives and the rooms are supposedly randomized every time the system boots the cartridge. When you start a new game, the same room layouts are used.
Conclusion
ScubaVenture was probably intended for younger players, as the game is much more simple than Mouser. While River Raid probably influenced the game's development, it quickly becomes repetitive in a way that River Raid does not. Each time you complete a section in River Raid, a new section appears. In ScubaVenture, each time you complete the section, the same section appears until you get all the treasures.
Mouser reminds me of Clu Clu Land for the NES, although Mouser came first. It is a very frustrating game due to the way the game moves the walls. You have to think about the direction the wall moves and hope you actually get it to move in the direction you want. The mice always seem to move in a pattern just one square away from being trapped. The timer runs down very quickly while you painstakingly try to manipulate the mice into your traps. Mouser is also buggy in that you can die upon entering a screen where a mouse happens to be in the same place as the entrance.
ScubaVenture and Mouser, both programmed by Nasir Gebelli, are very minimalist, enigmatic games. As Gebelli only had 8,192 bytes to fit the program in (they use 8KB cartridges), you can understand why they lack anything beyond the minimum necessary to make playable games.
Gebelli himself is something of an enigma, as he began programming games for the Apple II, then he did these PCjr. games and some years later worked for Square in Japan programming Rad Racer, Final Fantasy 1-3 and Secret of Mana. Thereafter, he quit video games altogether and has not returned to them, despite his obvious talents.
Gebelli's PCjr. games lack polish, which is very unusual as IBM released them and shipped them on expensive cartridges. ScubaVenture has some very impressive smooth vertical scrolling and supports two player simultaneous play. Mouser is more of a puzzle game requiring a fair bit of strategy. Both use the PCjr.'s 160x200x16c mode for colorful low resolution graphics and 3-voice sound.
Common Controls
Press F1 for one player and F2 for two player (That is Fn and 1 or 2 on the PCjr. keyboard). If left untouched, the programs will enter a demo mode. Both games use the keyboard by default. They can use joysticks by pressing the J key on the keyboard. You can return to the keyboard by pressing the K key on the keyboard. Press Esc to pause. Each uses the cursor control keys and the spacebar or the joystick positions and button 1 on the joystick. When your game is over, you will not be returned to the title screen, so press F1 or F2 to start a new game.
ScubaVenture
 |
| Title Screen |
 |
| Divers, Eel, Score, Fish |
 |
| Keys and more Keys |
Eventually, the tunnel will loop around. This will allow you to try to obtain a(nother) treasure. The cavern will loop until you have obtained all the treasures or have lost all your lives. Once you have obtained all the treasures, you will move onto a different tunnel.
 |
| Treasure Boxes |
 |
| Obstacles |
 |
| More Obstacles |
 |
| Two Player Mode |
 |
| Title Screen |
 |
| Starting Out |
 |
| I trapped a mouse! |
 |
| The Flashlight |
 |
| Dark Rooms and a Female Mouse |
Two players alternate in trying to clear their rooms. If the player touches a mouse or runs out of time, he loses a life. Each player has three lives and the rooms are supposedly randomized every time the system boots the cartridge. When you start a new game, the same room layouts are used.
Conclusion
ScubaVenture was probably intended for younger players, as the game is much more simple than Mouser. While River Raid probably influenced the game's development, it quickly becomes repetitive in a way that River Raid does not. Each time you complete a section in River Raid, a new section appears. In ScubaVenture, each time you complete the section, the same section appears until you get all the treasures.
Mouser reminds me of Clu Clu Land for the NES, although Mouser came first. It is a very frustrating game due to the way the game moves the walls. You have to think about the direction the wall moves and hope you actually get it to move in the direction you want. The mice always seem to move in a pattern just one square away from being trapped. The timer runs down very quickly while you painstakingly try to manipulate the mice into your traps. Mouser is also buggy in that you can die upon entering a screen where a mouse happens to be in the same place as the entrance.
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