Dumping/reverse engineering MSX models thread

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Par mcolom

Champion (276)

Portrait de mcolom

06-11-2022, 02:42

Hi all!
I've just dumped the ROM of the Philips_NMS_800 given that the wiki says "Philips NMS 801 is emulated and should be the same. For validation a ROM dump would be needed. See this thread for details". Result: they're the same. I'll update the wiki soon.

I did the following on the MSX and saved the WAV on my Linux computer:
bsave"rom1",0, &h3fff, 0
bsave"rom2",&h4000, &h7fff, 0

I loaded the WAVs in openMSX and saved a debuggable of the RAM:
cassetteplayer rom1.wav
bload"cas:", &h8000
save_debuggable Main\ RAM emu1.bin 0x8000 0x4000

cassetteplayer rom2.wav
bload"cas:", &h4000
save_debuggable Main\ RAM emu2.bin 0x8000 0x4000

cat emu1.bin >> chained
cat emu2.bin >> chained

$ shasum chained
21329398c0f350e330b353f45f21aa7ba338fc8d chained
$ shasum nms801_basic-bios1.rom
21329398c0f350e330b353f45f21aa7ba338fc8d nms801_basic-bios1.rom

Par sdsnatcher73

Prophet (3662)

Portrait de sdsnatcher73

06-11-2022, 07:24

Nice, you can update the Wiki if you like Wink

Par mcolom

Champion (276)

Portrait de mcolom

06-11-2022, 11:31

Done!
By the way, it seems the emulation of the VDP is not very accurate with openMSX (and yes... I know it's extremely complicated!). The real machine is adding the typical artifacts which happen when you write too fast, but... even in games that show fine with the 9918 or the T6950A! So probably the TMS9129NL has probably less access windows compared to his siblings. I can see clearly the difference with the border bars when loading a game.
Anyway, actually the NMS 800 is not even an MSX strictly speaking, so no need to dedicate much time on this Smile

Par Manuel

Ascended (19058)

Portrait de Manuel

06-11-2022, 13:03

TMS9129NL is used also in several MSX machines right?
As far as I know, according to the openMSX XML files:
AVT_DPC-200.xml
Bawareth_Perfect_MSX1.xml
Daewoo_DPC-200_FR.xml
Eurohard_Dragon_MSX.xml
Fenner_SPC-800.xml
Frael_Bruc_100_1.xml
Frael_Bruc_100_2_1.2.xml
Frael_Bruc_100_2.xml
Goldstar_FC-200.xml
Olympia_PHC-2.xml
Panasonic_CF-2700_DE.xml
Panasonic_CF-2700_DE.xml
Panasonic_CF-2700_GB.xml
Philips_VG_8000.xml
Philips_VG_8010.xml
Philips_VG_8020-20.xml
Philips_VG_8020-20.xml
Pioneer_PX-7UK.xml
Sony_HB-101P.xml
Sony_HB-101P.xml
Sony_HB-201P.xml
Sony_HB-501P.xml
Spectravideo_SVI-728_DK.xml
Spectravideo_SVI-728_ES.xml
Spectravideo_SVI-728_SE.xml
Spectravideo_SVI-728.xml
Talent_DPC-200.xml

Par mcolom

Champion (276)

Portrait de mcolom

06-11-2022, 16:01

Yes, but I'm not sure if it's exactly the same as the TMS9129NL.
Doing a grep all over the XMLs, it only finds occurrences in Frael_Bruc_100_2.xml, Philips_VG_8020-20.xml, Sony_HB-101P.xml, Frael_Bruc_100_1.xml, and Eurohard_Dragon_MSX.xml.

This is what I obtain with the emulator (left) and the real thing (right).

It should not be a tape-loading problem, since I'm doing it from my phone.
Well, if someone could try, say in the Sony HB-101P or any of that list, it'd be great to compare.

Par Manuel

Ascended (19058)

Portrait de Manuel

06-11-2022, 19:32

I guess it's not related to the VDP itself, but to some circuitry around it... who knows.

Par mcolom

Champion (276)

Portrait de mcolom

07-11-2022, 01:46

Yes, I'm starting to think the same.
I suspect that perhaps one or more VRAM chips are bad, after other artefacts I'm seeing. Anyway, I guess it's already a bit offtopic for this thread!

Par cbsfox

Champion (402)

Portrait de cbsfox

07-11-2022, 11:52

Hi guys.
Don't use BSAVE to capture the ROMS.
Use Power Chupim, the most advanced tool to do that.

Download it here: https://1drv.ms/u/s!AlpEtfGjLbhmhsZXpXIR8Sd6qCJWuQ

Par Louthrax

Prophet (2435)

Portrait de Louthrax

07-11-2022, 13:09

Manuel wrote:

I guess it's not related to the VDP itself, but to some circuitry around it... who knows.

This looks like the "too fast acesses to MSX1 VDP" not beeing emulated by openMSX (or is it now ?).

Par mcolom

Champion (276)

Portrait de mcolom

07-11-2022, 16:10

cbsfox wrote:

Don't use BSAVE to capture the ROMS.
Use Power Chupim, the most advanced tool to do that.

Well, this MSX1 machine doesn't have a disk drive, not even a single cartridge slots!
BSAVE worked well for this.

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