No More About The KayPro Diskette...

A project log for Improbable AVR -> 8088 substitution for PC/XT

Probability this can work: 98%, working well: 50% A LOT of work, and utterly ridiculous.

Eric HertzEric Hertz 03/03/2017 at 20:520 Comments

*This* "project page" is about installing an AVR in the CPU-socket of an 8088-based PC/XT computer.

If you've read the recent logs, you know I've gotten a tad-bit sidetracked on what I thought was going to be a one-night-endeavor and turned into several weeks.

So, now... There's a new "project page" for that, and I'll quit yammering about it *here*.

#Omni4--A KayPro-based Logic Analyzer

(See the next log in that endeavor here: )


Since that guy's occupying so much time/space, it'll probably be a while until I revisit *this* project. But here's a quick overview of where *this* project is at, currently.

I've managed to plop the AVR (ATmega8515) into the CPU socket and interface with components via the '8088-bus'.

Can read/write all 640K of DRAM with nearly 100% reliability.

Can read/write the CGA card (in text-mode), in color, no less. And, after a bit of an ordeal, have managed to get the reads/writes down to near 100% reliability.

(Turns out, I was reading the "READY" (aka "WAIT") signal too early, so the CGA card didn't have time to respond that it wasn't yet ready).

As a side-thing trying to solve the CGA problem, I also can read/write the parallel port.


Future-endeavors, maybe... I've looked into the specs for my SoundBlaster card... and I think I've enough info in there to start producing sound without too much difficulty. Thankfully it can be done without using DMA, because I've little interest in learning to use that blasted thing.

Looks like there are basically two different systems on the sound-card. There's the raw-sample-based system (e.g. for playing/recording WAV files), but there's also a waveform-synthesizer-chip which can be used to generate surprisingly (to me) sophisticated waveforms...

Frankly, my artistry when it comes to graphics/sound is limited... So, I really don't know what I'll *do* with this thing when I get that running. (As is the status with the CGA card which is functional). Maybe some copy of some game... Tetris or something. But don't be expecting any "demoscene"-worthy demos coming from my endeavors.

I suppose I should probably get the keyboard working at some point... Though I could probably more-easily use the RS-232 port.


For now, back to backing-up that blasted floppy-disk.