Ok, I tried some other things and it's weird: If I remove my video card, the BIOS is starting and emits some beeps. If I then press a key, the floppy drive is running (and seems to look for something).

Probably it's more my video card that got bricked and prevent the BIOS to boot. If that's the case, not sure how I'll be able to unbrick it (without hot-plugging it after a successfull boot).

Louthrax wrote on 2023-12-23, 15:14:

So I think I'll have to extract and reflash the BIOS chip manually. I have an EPROM flasher here (that I mainly use for 8Bits […]
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So I think I'll have to extract and reflash the BIOS chip manually. I have an EPROM flasher here (that I mainly use for 8Bits consoles), and an image file (BAPM14A.BIN) of the P6BAP BIOS (targeted for the AWDFLASH.EXE tool).

I'm wondering if anyone here had already done that or have some advice on the procedure ?

Questions I have in mind before attemtping something:
1. Is the P6BAP-Me BIOS chip a standard EPROM ?
2. Is the BAPM14A.BIN a raw image (that could be flashed directly) ? It has a size of exactly 256KB, so I guess it is.
3. Is there an undocumented procedure to reflash the BIOS from the motherboard without extracting it ?

Yes have flashed many bios chips with my eeprom programmer. Is very easy to do if you have the proper software to work with your eeprom flasher.
1. Should be
2. Yes
3. Only if your boards boot block is not corrupted.

Curious why you tried to flash both the video card and the motherboard in same cycle ? That is always a no-no (trying to flash two diff parts at same time).
You flash one and check results, then if OK you flash the other. Also you should never alter your main config and auto bat files just to flash a part. Use a boot floppy and point it to the files on your HD.
Guess you sorta learned those last ones 😀

Ok now you need to find another video card just to make sure your board bios is OK. Don't monkey with the one you flashed until you know your board is OK. Any old PCI vid card would work for that....

Thanks Horun for your reply.

I put this "reflash everything" entry in my configuration so that in case of bad issue (no display or something else), I simply have to go down 6 times after boot and validate. Then the BIOS and Video Card are reflashed and a reboot is done.

I know it was working in the past (I used it several times), but I maybe changed the video card and did not update its BIOS file after that (I also restored my PC last week using old backups, maybe the BIOS they contained was outdated...).

I did that because my Windows 98 PC display is a Trinitron Sony TV, using a modified ATI BIOS for that purpose. This PC mainly launches MAME games, with (when supported) the same frequency / resolution as on the original arcade machines. I had lots of tweakings / updates to do in the ATI BIOS in order to make this working, and this AUTOEXEC.BAT entry has been very usefull in the past. It can also launch MS-DOS and Windows 98 (the Windows ATI driver shrinks down the rendering to CRT acceptable resolution).

I have a lot of other old video cards in my attic. Maybe if I manage to boot with another video card plugged (in another port), I could access the ATI card again and reflash it?

I'm a bit mad against me about what happened because I really struggled to find the right ATI video card at the time when I made this PC (that was 5 or 6 years ago).

I'm also wondering why a video card BIOS issue can block the main boot process ?

Ok, Windows 98 PC unbricked 😀 !

My final understanding of what happened is:

* The flashing of the motherboard in AUTOEXEC.BAT went wrong because being called with a wrong CONFIG.SYS entry, which has not the right memory configuration for flashing.

* My mainboard indeed has a "recovery" process that allows to boot to a floppy disk and reflash, but the presence of my ATI card (with a modified driver as mentionned above), blocks this process. So I only had to insert another video card to reflash the BIOS. Re-inserting the original ATI video card after that worked. When checking the boot process with the "other" (NVidia) card, some video card code is executed before going to the BIOS itself. I guess my modified ATI BIOS has some dependencies on the motherboard BIOS itself...