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FPGA Based IBM-PC-XT

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Re: FPGA Based IBM-PC-XT

#41

Post by drzaiusx11 »

This is exactly the type of content I come to HN for. Succinctly writen passion project posts like this one that actually inspire me to finish and document my own.

I started a (couple of) very similar project(s) for the VCS/2600 that I'm now motivated to take a second look at. One that used a modern 6502 equivalent, and another that was largely software based, but read and used the physical cartridges and controllers but passed the heavy lifting to software emulation.

That said, I do hope the author posts a follow-up on how the EGA graphics were implemented.

Re: FPGA Based IBM-PC-XT

#42

Post by drzaiusx11 »

drzaiusx11 wrote: post #41

This is exactly the type of content I come to HN for. Succinctly writen passion project posts like this one that actually inspire me to finish and document my own. I started a (couple of) very similar project(s) for the VCS/2600 that I'm now motivated to take a second look at. One that used a modern 6502 equivalent, and another that was largely software based, but read and used the physical cartridges and controllers…

I did end up publishing the libraries I wrote for VCS cart dumping [1] which handles the vast majority of custom bank switching schemes, with instructions on how to wire it to a rpi or Arduino to make a ROM dumper if anyone is curious.

Looks like past-me also posted an earlier/incomplete version of the paddle and joystick handler code as well [2]. I should find the finished one on my old laptop and push.

1. https://github.com/drzaiusx11/WiringVCS

2. https://github.com/drzaiusx11/AtariGamepad

Re: FPGA Based IBM-PC-XT

#43

Post by drzaiusx11 »

haxxorfreak wrote: post #6

I love the hard drive sound emulation! I find that modern restorations of vintage hardware using SD cards to emulate drives are missing an important part of the nostalgic experience when they just start up completely silently.

The attention the author paid to these little details really raises this project above the typical (XT) hardware clone. Put another way: I absolutely love this feature.

Re: FPGA Based IBM-PC-XT

#44

Post by drzaiusx11 »

nsxwolf wrote: post #18
dlcarrier wrote: post #4

The title is a bit misleading; it's running on an 8088-compatible CPU, and a 1 megabyte SRAM, with the FPGA containing the display adapter and drive controller, as well as the glue logic.

This build demonstrate what’s actually interesting about FPGA to me. A pure implementation might as well be a software emulator. Being able to interface real chips makes this really neat.

The author used the lattice fpga for exactly what it was designed for: glue logic. This fpga type isn't what you'd throw a couple of cpu cores on, it's more along the lines of replacing a few dozen 74xx series logic chips. I personally enjoyed the author using modern day chip equivalents instead of soft cores on an fpga. I find the latter to be much less interesting.

Re: FPGA Based IBM-PC-XT

#45

Post by larme »

ForOldHack wrote: post #29

I would like to have a xt and at and 386 in this tiny form factor, to play Rogue on the X T and try to compile nethack on the 286 version of Xenix and the 386 version of Xenix. I know from experience it will never compile on the 8088 version of Xenix. It will wreck your OS and filesystem.

Have you tried pocket 386? https://arstechnica.com/gadgets/2024/08/a-few-weeks-with-the...

Re: FPGA Based IBM-PC-XT

#46

Post by BirAdam »

I love this, but I do prefer just using the NuXT. The NEC V20 is a great CPU, my personal favorite. It's a better 8088 that maintains compatibility while increasing performance and offered a great price to consumers at the time of its introduction.

Re: FPGA Based IBM-PC-XT

#47

Post by bartread »

haxxorfreak wrote: post #6

I love the hard drive sound emulation! I find that modern restorations of vintage hardware using SD cards to emulate drives are missing an important part of the nostalgic experience when they just start up completely silently.

Yeah, for me there's something about the sound of the power supply, CPU and (sometimes) graphics card fans, coupled with the ticking of an old school hard disk that takes me right back to the nineties.

I know spinning disks were a thing for a lot longer than that, and were still pretty commonly used up into the 2010s, but they were in general much quieter than hard drives from the 90s.

Re: FPGA Based IBM-PC-XT

#49

Post by leeter »

dlcarrier wrote: post #4

The title is a bit misleading; it's running on an 8088-compatible CPU, and a 1 megabyte SRAM, with the FPGA containing the display adapter and drive controller, as well as the glue logic.

Honestly? I expected this to be talking about the MiSTer project FPGA core[1]. That has been tuned so it's capable of running the AREA5150 demo[2] which is an insane challenge (AFAIK the timings of the v20 break that demo). Not saying this isn't cool, but it's definitely not what I was expecting.

[1] https://github.com/MiSTer-devel/PCXT_MiSTer

[2] https://www.youtube.com/watch?v=tOmcgp99fEk

Re: FPGA Based IBM-PC-XT

#50

Post by kjs3 »

ForOldHack wrote: post #14
haxxorfreak wrote: post #6

I love the hard drive sound emulation! I find that modern restorations of vintage hardware using SD cards to emulate drives are missing an important part of the nostalgic experience when they just start up completely silently.

The floppy disk usually made this straight up honking noise . I had a V20, but at 10Mhz. Never had a problem, except for formatting floppies. The V20 has a few tricks up it's sleeve, with a few less clock cycles on some instructions, and a Z80 mode to run cpm. But,the real trick was to put real IBM roms in a clone board and run Xenix. When the clone roms are back in it still booted. Helped a lot to have a 2:1 Rll con…

Z80 mode to run cpm

8080 mode, not Z80. Did run CP/M, and I used 22nice for probably longer than needed. Unfortunately over time lots of cool software assumed a Z80, sooo...

Xenix was just pollute and delute - system V with some BSD thrown in

Which Xenix? It was originally V7 based, and 'upgraded' to System III around version 3. I forget what it looked like between version 3 and version 5.x, where it became System V based (+ stuff).

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