Taking Color out of the Color Graphics Adapter

When IBM released the Personal Computer back in 1981, it gave the buyer two choices for the video output. The buyer could buy a monochrome card and a special high resolution green screen monitor to go with it, or a color card and connect it to a color monitor. The buyer could even run both cards in the same system. If someone was on a tight budget, they could use a monochrome monitor with a color card, in this blog article we will explore what the results of that would be.

Tandy 1000 EX & HX vs. Color Computer 3 vs. Commodore 128 vs. Apple IIc - Which is the Better All-in-One?

In the calendar year of 1986 Tandy introduced two all-in-one computers, the Tandy 1000 EX and the Tandy Color Computer 3. Both were competitively priced at $799.00 and $219.95, respectively. At first the budget-conscious consumer may have chosen the CoCo 3 over the EX. By the next year the price of the EX had dropped by $100 while the Tandy 1000 HX took its prior price. At the same time the CoCo 3 dropped in price by $20, where it would stay until it was discontinued in 1990. The HX would displace the EX and eventually fall to $699 before it was also discontinued in 1990. In this article we will compare the features of these all-in-ones feature by feature and try to determine which would have really been the better purchase.

Tandy Deskmate - Tandy's Ace in the Hole

In 1984 Tandy released a software package called DeskMate. DeskMate was a basic suite of office productivity software and Tandy would bundle the software with its computers or sell it in Radio Shack stores and via mail order for a relatively low price. DeskMate, while little remembered today, was a key factor in putting Tandy computers in many homes. Let's take a look at how the suite did that and evolved over time.

Tandy Video vs. EGA - Battle of the 16-colors Graphic Adapters

When the PC was first released in 1981, IBM designed the Color/Graphics Adapter (CGA) card, a card that could display 16 colors on a special high quality RGBI monitor through a digital output.  While CGA could only display all those 16 colors on the screen at the same time in text modes absent trickery, IBM's 16-color digital RGBI video display standard proved quite durable.  IBM used the same color standard in its IBM PCjr. video graphics adapter in 1983 and returned to the standard the next year in the form of its Enhanced Graphics Adapter (EGA).  When Tandy released its Tandy 1000, which was designed as a clone of the PCjr., it included the graphical capabilities of the PCjr and would later expand on them.  The Tandy Graphics Adapter (TGA) really popularized 16-color full screen graphics but by the late 1980s most games would support Tandy and EGA graphics.  So which is better?  In this blog article we will attempt to answer this question.

Tandy 1000 Chip Replacements

The Tandy 1000s, especially the older ones, are rather reliable as non-IBM manufactured PCs go.  They tend to continue working year after year.  But inevitably they will fail, and something they cannot be easily fixed because a chip went bad.  Tandy was good enough to socket major chips in most of its machines (DIP and PLCC) and frequently reused chips from machine to machine.  Tandy sometimes would use off the shelf chips, sometimes custom chips and sometimes programmable logic.  In this blog article I will identify the major chips each system uses in order to help people find suitable replacements, if possible.  

Tandy 1000 EX and Tandy 1000 HX - The All-in-One Tandys

The Tandy 1000 EX was released in mid-1986 ($799) and the Tandy 1000 HX released in mid-1987 ($699) .  They were Tandy's "entry-level" PC-compatible models, containing everything you need to run PC and MS-DOS software in a fully self-contained unit by means of the built-in keyboard. The Tandy 1000 SX ($1,199) was released alongside the EX and the Tandy 1000 TX ($1,199) accompanied the HX. Due to their low cost and despite their increasingly unimpressive specifications, they still sold very, very well.  Lets talk about their abilities, their upgrades and their differences.

Random Computer and Video Game Musings

Sometimes I have something to say but the topic is not worthy of a full blog post.  In this case I have gathered four topics which I believe are interesting but not necessarily related and put them into this consolidated blog post.  Enjoy!

IBM Composite Artifact Color Games and Related Topics

Top - Direct Colors Old CGA & New CGA
Bottom - High Resolution Artifact Colors Old CGA & New CGA

Back in 2013 I gave an overview of composite color usage on the IBM PC platform.  I included a list of all games I knew about or could find which supported composite color graphics.  Now, 10 years later, new information has made that list less than inaccurate and less than fully inclusive.  Let's talk about these games and give a new, more accurate list.  I will also talk about other topics related to CGA and color in more detail below.  

The Saga of the Color Brown in the Early Years of the PC

top left: RGB monitor without intensity bit, bottom left: RGBI monitor without brown correction, top right: RGBI monitor with 33% brown reduction (IBM 5153), bottom right: RGBI monitor with 50% brown reduction (EGA/VGA/Tandy)

In 1980-81 IBM developed a graphics card for its new IBM PC called the Color/Graphics Adapter.  This card was designed to display 16 colors on a compatible CRT monitor via a 9-pin digital video port.  IBM defined the colors in its Technical Reference Manual using a 4-bit binary code.  The CGA could also display colors with a composite video connector on the card.  It is the evolution of the display of one of those colors, color 6, commonly but yet simplistically referred to as brown, that we are interested in today.

Tandy 1000 Gray and Peach Label Releases

When Tandy released its Tandy 1000 computer in November, 1984, it needed software to tell that would demonstrate the system's PC compatibility and its enhanced features.  Tandy had been both a software developer as well as publisher for its TRS-80 computers and its Color Computer, but those were computers that Tandy had brought into the world.  For the Tandy 1000, Tandy was entering into a market already established by IBM and already had a very large number of software developers publishing for that platform.  As the Tandy 1000 maintained a large degree of PCjr. compatibility and was essentially PC compatible, there was already a significant number of titles which could take advantage of the enhanced graphics and sound derived from the PCjr.  Companies like Sierra On-line and Spinnaker Software had invested heavily in PCjr. software and were eager to find additional avenues to sell their games, even more so once IBM announced it was discontinuing the PCjr. in March, 1985.  Tandy was happy to make publishing deals if they released Tandy 1000 specific versions of their games.  Let's look at those versions.

Accelerating your Tandy 1000s

The Tandy 1000s have unique graphics hardware and sound hardware that was supported for a long time.  The number of Tandy 1000s was so large that many games from prestige publishers released after 1984 would have support for Tandy 16-color graphics and/or Tandy 3-voice sound.  While there were other graphics solutions which provided 16-color full screen graphics at a resolution of 320x200 pixels, only the Tandy 1000 series had any significant support in games.  Additionally, the Adlib and other expansion sound cards did not get PC gaming support until September of 1988.  During the lifespan of the Tandy 1000s, the system speeds were generally keeping pace with games, but by the end of the 1980s the 1000 line was not getting any faster, but games and applications were becoming increasingly demanding.  In this article let's talk about the benefits and drawbacks of installing CPU accelerators in your Tandy 1000s.

List of PCjr. and Tandy Exclusive Enhanced Games

The IBM PC computing platform supported gaming from the beginning, but at first its graphical and sound capabilities were not that much more advanced than an Apple II's. Other inexpensive home computers of the day (Atari 800, Commodore 64, TI-99/4A) could run rings around the IBM PC in the video and audio departments. IBM sought to improve its PC line's graphics and sound in an affordable system which became the PCjr., but that was a flop.  Tandy cloned the graphics and sound of the PCjr. and put it into a much more PC-compatible system, the Tandy 1000.  Between the two, the exclusive PCjr./Tandy graphics and sound hardware received wide support from game developers in the mid and late 1980s.  In this article, I will attempt to give a definitive list of games which have "better" graphica or sound on a PCjr. or Tandy 1000 due to this support or have unique video and audio support even if the game can utilize EGA, VGA, Adlib, Game Blaster or Sound Blaster or MT-32.

The Gotek Floppy Drive Emulator in the IBM PC World

The Gotek floppy drive emulator is a simple, cheap and little device that, as its name says, emulates a floppy drive.  There are many varieties of these devices and they usually come with a USB port on the front of the unit and a 34-pin header + 4-pin power header on the back.  While originally intended to replace disk drives in industrial, sewing and musical equipment, they can be used with standard PC floppy controllers.  However, as they come they are at best diamonds in the rough, so in this blog entry I will describe how to make these devices more useful for vintage IBM PCs and compatibles.

Expanding Vintage IBM PC & Compatible Display Options - the GGLabs CGA2RGB Converter

GGLabs' CGA2RGB (courtesy of GGLabs)

Getting a high quality and proper video signal from an IBM CGA or EGA card or an IBM PCjr or Tandy 1000 without their specialized monitors can be difficult.  These computers used specialized RGB monitors to give a high quality solution using digital signals to tell the monitor which color to display.  Unfortunately this standard was not really adopted outside of the expensive PC compatibles and most RGB monitors only accept an analog signal.  When VGA and its analog RGB signal format became standard, support for the older digital RGB format went away.  In this blog entry I am going to examine an inexpensive converter that can help you adapt your vintage PC compatible's digital RGB video output to the more accessible analog RGB video output.

The Obscure Tandy 1000 Models

When I have talked about the Tandy 1000s in the past, and I know it has been a while, I have focused my discussions on the Tandys that were available to purchase by members of the public at Radio Shack stores.  If you walked into a Radio Shack store in the 1980s and had $1,000 to spend, you could walk out with an IBM PC compatible computer.  The 1000 line was cheap, fully functional as PC clones and played games as well as or better than machines that cost many times their price.  But Radio Shack was not the only source from which you could obtain a 1000, and the 1000 hardware was also available to institutional buyers.  So in this blog entry I am going to pull together every scrap of information I can find on the rarest, most obscure Tandy 1000s in existence.

More Keyboard Adapters : The Tandy 1000 Keyboard to Tandy 1000 TL or SL

The earlier Tandy 1000s, the 1000, 1000A, 1000 SX and 1000 TX came with a 90-key Tandy Keyboard.  The Tandy 1000 EX and HX had the 90-key Tandy Keyboard built in.  This keyboard uses its own communications protocol and timing and is not compatible with an IBM PC, XT or AT or their clones.  This keyboard uses an 8-pin DIN plug.

The later Tandy 1000s from the TL and SL onward came with 101-key keyboards.  These keyboards, called the Tandy Enhanced Keyboard, were an autoswitching keyboard that could work in an IBM PC, XT, AT or their clones.  This keyboard uses a 5-pin DIN plug and do not work in an earlier Tandy 1000.

In the technical reference manuals for the TL and SL, which are the last Tandy technical reference manuals available online, the keyboard controllers do mention Tandy 1000 Keyboard compatibility.  These computers have a 7-pin DIN connector even though an XT or AT keyboard only uses four pins.  The schematics indicate that the extra pins are used for Tandy 1000 keyboard-specific signals.

The Northgate Omnikey to Tandy 1000 SX & TX Keyboard Adapter

The Tandy 1000 computers, more specifically the early Tandy 1000s, had many good features, graphics, sound, expansion, performance, integrated peripherals.  To save development costs, Tandy imported some of its designs from prior, non-IBM PC compatible computers.  The Tandy 1000 card edge printer port can be traced back to the TRS-80.  The Tandy 1000 joystick ports came straight from the Tandy Color Computer.  And finally, the Tandy 1000 keyboard is the same keyboard used in Tandy's MS-DOS (but not IBM PC) compatible Tandy 2000.

The 90-key Tandy 1000 keyboard is not exactly a pleasure to use.  Its layout is cramped and awkward, its keys are mushy and there is no tactile feedback.  Compared to the IBM PC or IBM PC AT keyboard, it feels cheap.  Typing mistakes are frequent with this keyboard.  It has some odd key omissions.  There is no Scroll Lock, and while there is a separate Home key, there is no separate End, Page Up, Page Down, +, -, or * keys.  The shift keys are too small.  While it does have F11 and F12, software made during the Tandy 1000 (except by Tandy) lifespan rarely used these keys.

Finally, the Tandy 1000 has the dreaded Hold and Print keys.  Both keys are next to important keys like Enter, Alt and Num Lock,  The Hold key acts like a true Pause key, everything is frozen until you hit the Hold key again.  People who do not know or forget how the Hold key works may think their computer has crashed.  However, the really evil key is the Print key.  Press this key twice and, unless you have a printer attached to your computer, your computer will freeze as it vainly tries to print what you are typing on the screen. Your computer will appear to freeze.  IBM avoided this issue by assigning the function to Ctrl+Print Screen.

Boulder Dash - PC Speed and Joysticks

Boulder Dash was originally released for the IBM PC and PCjr. in 1984 by First Star Software.  The disk included two separate executables, one for the IBM PC and one for the IBM PCjr.  The disk was a PC booter.

The IBM PC executable is serviceable but not particularly impressive.  There is a distinct lack of animation on the title screen and for the amoeba tiles.  There is also no color-cycling effect for the diamonds.   It is debatable whether the game really uses composite color graphics.  Sound effects are weak even by PC speaker standards.

The IBM PCjr executable, on the other hand, is much, much more impressive.  It uses the 3-voice PCjr. chip for music and sound effects.  It supports 16-color graphics with full animation and color cycling.  Despite the PCjr. being slower than the PC, it does not suffer from a lot of slowdown, despite the extra effort.  Compare these pairs of screenshots from the PC and PCjr. executables :

The PC Joystick to Tandy 1000 Joystick Port Adapter

IBM PC-compatible joysticks using the DA-15 connector came in all shapes and sizes.  Some have a hat switch, some have a throttle wheel, and many are quite durable.  The CH Flightstick Pro is among my favorite PC joysticks.  Its large enough to fit in my hand, has easy movement and feels very precise.

Unfortunately, Tandy 1000 users do not have many options, thanks to the 6-pin DIN connector the 1000 line used.    The official Tandy joystick line consists of the miserable black box joystick with the single button and non-self centering stick, the Deluxe Joystick which fixes those issues but is still rather boxy and uncomfortable, and the Pistol Stick Joystick, which has a handle but is really basic.  Not many third parties released joysticks with the Tandy plug, but in this blog article, I will tell you how to adapt any standard PC-style joystick to work in a Tandy 1000 joystick port.

The Tandy 1000 Digital Joystick Adapter

IBM PCs and compatibles had an analog joystick interface.  The Tandy Color Computer and clones like the Dragon 32/64 computers also had an analog joystick interface.  Inside an PC or CoCo joystick were a pair of potentiometers.  The chief difference between the two interfaces is how the potentiometers were connected.  PC sticks used the potentiometers as variable resistors, wiring two of the three terminals, one of which to +5v and the middle would be connected to the interface's input.  CoCo sticks used the potentiometers as voltage dividers, where all three terminals would be connected, one outer terminal to +5v, one outer terminal to ground and the middle terminal would be connected to the interface's input.

In the early days of home computers, a joystick could be used for more than just playing games.  It could function as a cursor controller like a mouse, which was useful for drawing programs.  It could also be used for flight simulators, where the analog control could be appreciated.  Most home computer games from the 1980s that support a joystick were ported or derived or inspired by the popular home console and arcade games of the time.  Games like Pac-Man, Pitfall and Space Invaders did not really need an analog stick, they usually used digital joysticks.  When platforming games like Super Mario Bros and Prince of Persia became popular, they often or exclusively used digital gamepads.