VOGONS


First post, by TheGreatCodeholio

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It seems that at one time, there were technical manuals available on the web https://web.archive.org/web/19970301075524/ht … p/tech_man.html but they seem to be long gone. Googling for the information is fruitless.

I'm interested in documents covering all the BIOS calls, I/O ports, etc. things that both a programmer and emulator developer would want to write code to the hardware, which is also very sparse and hard to find.

If anyone has any links or files they can post to provide this information, please post it here. No spam.

I apologize for the timing of this post, but this is not an April Fools joke. Thank you.

DOSBox-X project: more emulation better accuracy.
DOSLIB and DOSLIB2: Learn how to tinker and hack hardware and software from DOS.

Reply 2 of 16, by crazyc

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UNDOCUMENTED 9801/9821 Vol.2 http://www.webtech.co.jp/company/doc/undocumented_mem/
upd7220 datasheet http://bitsavers.trailing-edge.com/pdf/nec/uP … anual_Dec85.pdf
Neko Project 2 https://github.com/nonakap/xnp2
MAME https://github.com/mamedev/mame/blob/master/s … vers/pc9801.cpp

Reply 4 of 16, by TheGreatCodeholio

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Excellent! I hope this shows up on Google search for anyone else interested in PC-98 I/O ports and hardware.

Now to see if I can figure out enough Japanese to read that documentation... 😀

DOSBox-X project: more emulation better accuracy.
DOSLIB and DOSLIB2: Learn how to tinker and hack hardware and software from DOS.

Reply 5 of 16, by crazyc

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I learned more than anyone rational would want to know about that machine while working on the mess emulation. If you have any questions, just ask. BTW google translate does a marginally understandable job on the undocumented_mem files.

Reply 6 of 16, by TheGreatCodeholio

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crazyc wrote:

I learned more than anyone rational would want to know about that machine while working on the mess emulation. If you have any questions, just ask. BTW google translate does a marginally understandable job on the undocumented_mem files.

I appreciate it. I'm putting in the framework now for DOSLIB to compile versions of it's libraries for PC-98 systems. I understand some of the hardware (like the PIT timer and IDE) is sort of the same interface, just moved around to different I/O ports, spaced two I/O ports apart for some reason and interleaved even/odd numbers between devices. Weird.

The intent is for DOSLIB to open up cross-development to PC-98 systems the same way DOSLIB opens up IBM PC/XT/AT cross-development now. I will be writing code to run in PC-98 emulation, and hopefully, run on actual PC-98 hardware.

https://github.com/joncampbell123/doslib

DOSBox-X project: more emulation better accuracy.
DOSLIB and DOSLIB2: Learn how to tinker and hack hardware and software from DOS.

Reply 7 of 16, by crazyc

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I understand some of the hardware (like the PIT timer and IDE) is sort of the same interface, just moved around to different I/O ports, spaced two I/O ports apart for some reason and interleaved even/odd numbers between devices. Weird.

There is a sane reason to interleave the devices like that. Even the original pc9801 had an 8086 so it has 16 data lines which is a pain to use with 8bit devices. That way they could use A0 as a chip select and route D0-7 to one device and D8-15 to the other.

Reply 8 of 16, by TheGreatCodeholio

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crazyc wrote:

I understand some of the hardware (like the PIT timer and IDE) is sort of the same interface, just moved around to different I/O ports, spaced two I/O ports apart for some reason and interleaved even/odd numbers between devices. Weird.

There is a sane reason to interleave the devices like that. Even the original pc9801 had an 8086 so it has 16 data lines which is a pain to use with 8bit devices. That way they could use A0 as a chip select and route D0-7 to one device and D8-15 to the other.

So what happens if you do a 16-bit I/O write, do you talk to two chips at once? Or does it still decode A0 as chip select and let the chip take in all 16 bits? Or... is that undefined behavior?

DOSBox-X project: more emulation better accuracy.
DOSLIB and DOSLIB2: Learn how to tinker and hack hardware and software from DOS.

Reply 10 of 16, by SA1988

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crazyc, a quick question, why does NT 4.0 here suffer from the BSOD 0x7b (second parameter is 0xc0000034) in general? is it related to the DMA or the IDE code? (not on MAME as it's already solved)

And btw, I'm using this fork of NP21 and win2000 PC98 works there, but not NT 4.0 or 3.5x: https://sites.google.com/site/np21win/home

Reply 11 of 16, by crazyc

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Does np21w have PCI IDE emulation? If not than it wouldn't be DMA as PC98 ISA (acutally CBUS but the differences aren't important) IDE, like the AT, lacks any useful DMA support. The problem might not even be IDE though, could be a CPU emulation issue.

Reply 12 of 16, by SA1988

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well, I can post a screenshot and yes and no, PCI is partially supported on np21w, though not for IDE.
np21w, like the standard mainline one, has a defective FPU, but I don't think it's the problem.

Reply 15 of 16, by TheGreatCodeholio

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I know I haven't spoken in this topic for awhile but I just finished adding basic PC-98 emulation to DOSBox-X.

In the latest commit (not the latest Win32 binary) you can set machine=pc98 to enable it.

You will also need ANEX86.BMP for the character ROM to display the full character set.

So far I can run:

Edge
DGA
Tetris (PC-98 verson)
Pacman (PC-98 version)
Rude Breaker

and of course:

Touhou Project (2 through 5).

Github issue tracker for this progress:

https://github.com/joncampbell123/dosbox-x/issues/106

DOSBox-X project: more emulation better accuracy.
DOSLIB and DOSLIB2: Learn how to tinker and hack hardware and software from DOS.

Reply 16 of 16, by TheGreatCodeholio

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I just finished adding more PC-98 emulation. I've decided to start releasing Windows binaries again, though Linux will still be my primary dev target.

I also borrowed the FM synthesis emulation from Neko Project II and ported it to DOSBox-X, so your favorite games should have some music and sound effects. MIDI emulation was adapted as well, so you can use your Windows MIDI device or Linux with Fluidsynth to hear it if the game uses MIDI playback.

Enjoy.

https://github.com/joncampbell123/dosbox-x/commits/master

DOSBox-X project: more emulation better accuracy.
DOSLIB and DOSLIB2: Learn how to tinker and hack hardware and software from DOS.