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Thomson TO16 BIOS splash screen (in ROM)

[Linked Image from i.imgur.com]

not bad for an XT compatible ...


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Looking for a bit of guidance here:

at.cpp: Most of the 486 BIOS versions I've left to add are of the 128K variety (compressed, BootBlock etc.) that will either only show a blank screen or boot into the BootBlock BIOS at the moment.
Should I add these or wait for the ones already present to have their chipsets emulated?

pc.cpp: What are the criteria for classifying a computer as "working" (removing the MACHINE_NOT_WORKING remark)? I'd like to go through the NOT_WORKING ones and check those.

at.cpp: Are these criteria applicable to the 286 machines as well? If yes, I'll test them as well.


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"Working" in a PC context means you can install DOS onto a hard disk and run games and applications.

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Go ahead and add everything, there's no telling when the chipset emulation will get worked on and in the meantime having the ROMs in MAME means they won't disappear.

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I keep coming across ROM dumps for PC BIOS that have different loading addresses:

Code
EA 4C 80 00 F0 30 38 2F 31 33 2F 39 31 00 FC DB


where a standard BIOs has

Code
EA 5B E0 00 F0 30 33 2F 31 35 2F 39 31 00 FC 00


Both examples are from 286 motherboards.

The first one doesn't run in MAME, but in PCEM, look for 2ctc001, a GW286CT motherboard.

Is this a feature of the chipset (C&T SCAT in this case) that isn't emulated yet in MAME or a bad dump that is somehow worked around in PCEM?

Last edited by rfka01; 12/30/19 09:17 PM.

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Slowly getting S3 Virge BitBLTs somewhat working...
[Linked Image from mahlemiut.marpirc.net]


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That's awesome. Should improve performance for Win 3.x.

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Originally Posted by rfka01
Is this a feature of the chipset (C&T SCAT in this case) that isn't emulated yet in MAME or a bad dump that is somehow worked around in PCEM?


Different loading addresses are uncommon possibly because there's software the checks to make sure it's running on something fully AT compatible but it shouldn't affect much. There are several other bioses that don't boot because of missing chipset support. It's likely that there's some magic values that can be returned to make them happy that doesn't require full chipset emulation and that's what pcem does.

Last edited by crazyc; 12/30/19 11:27 PM.
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Actually, PCem's fork, 86Box, more or less fully emulates the SCAT chipset AFAIK. It also has plenty of machines emulated that use that chipset too.

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AMI PC BIOS versions show the amount of RAM you throw at the machine - e.g. they test RAM up to 16384KB if you start the emulation with -ramsize 16M.

Award BIOS versions make a distinction between testing RAM and sizing RAM.

On the older "list type" Award BIOS versions, e.g. v4.20 you'd get the amount of RAM physically installed in the "testing" categories and two lines before that it'd show the amount minus the 384K ROM area in the "sizing" categories split up between System and Extended Memory (capitalization is Award's smile )

[Linked Image from i.imgur.com]

The later, e.g. v4.50 Awards do the count up testing on the first page, the sizing on the second one:

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]

in MAME, we're getting 384K on top of the "physically" installed memory, 16768K, and instead the "sizing" category matches the "-ramsize" parameter.

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]


unless, of course, you're running so025r2, a Soyo board which is in my next pull request, where the RAM test makes a rather suspicious jump from 16MB to 256MB smile

[Linked Image from i.imgur.com]


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