Friday, December 22, 2017

Parallel & Serial Sound Card Emulation Options for your Vintage PC

In the beginning the Intel 8088 and 8086 CPUs only implemented, Real Mode, where a program had total control over all aspects of a system.  Real Mode's main issue, other than it was limited to 1MB of RAM, was that multitasking was almost impossible to accomplish.  Then the 286 CPU implemented a Protected Mode and allowed the CPU to address 16MB in that Mode, but few applications used it because DOS required Real Mode. Finally, the 386 CPU implemented a far more usable Protected Mode and a Virtual 8086 Mode (V86).  V86 Mode allowed the CPU to run multiple instances of Real Mode where each program would be given access to up to 1MB of RAM for their own purposes without overwriting another program's data.  To each program running in V86 Mode, it would appear to it as though it had full control over the PC.

As a byproduct of V86 Mode, Expanded Memory, which had been implemented with expansion cards on 8088 & 286 machines, could be emulated with Expanded Memory Managers (EMS).  The most popular EMS was EMS386, which came with MS-DOS 5.0 and later.  There were other EMS softwares like QEMM and JEMM.  EMS also allowed a user to trap writes to memory locations and I/O ports.  Sound cards invariably wrote to I/O ports on a PC to make sound.  Eventually it was discovered that this port trapping capability could be used to emulate sound cards.  Software drivers of recent and ancient vintage have been being this feature, or implementing their own, to emulate sound cards and chips for systems that may not or cannot use them.  Let's take a look at some of these devices and methods.

Saturday, December 9, 2017

Analogue Nt Mini : Browsing the Core Store Pt 2, AV and Future Predictions

In what is likely to be the penultimate article in my Analogue Nt Mini series for some time I intend to devote some time to a few of the more interesting cores remaining in the system, then discuss the video output from the NES.  Finally, I will offer my predictions for the future.

Saturday, December 2, 2017

Atari Flashback 2 - The Only Flashback Worth Anything

While browsing in one of my local thrift stores, I encountered an item I had been wanting for a long time, the Atari Flashback 2.  This mini-console with its built in games had interested me ever since it first game out.  Even though I already had a light-sixer 2600 and a Harmony Cartridge, I still wanted one of these.  The box was marked at $24.99, but the seal seemed to be still intact, so the purchase was a no-brainer for me.  In this blog post, let me describe the system, its capabilities and talk about its included games and its legacy.  This review may be 12 years too late, but I could not let this opportunity pass without comment.