Chkcpu wrote on 2025-02-27, 19:55:

Hi evanboonie, […]
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Hi evanboonie,

That is quite a challenge you have there, getting a K6-2 to run on the Apple 1997 PC Compatibility Card!

Looking into the AMI BIOS9.ROM, I see this card uses the OPTi 557M Viper-M chipset. This is a 1995 chipset for socket 5 boards. But the BIOS9.ROM looks like it is from 1997 and it has the expected CPU support from that era: Intel Pentium and Pentium MMX, Cyrix 6x86 and 6x86MX, and AMD K5 and K6. So no support for any IDT WinChip.

The K6 support in this BIOS is only for the original K6 model 6, the 2.9V/3.2V Vcore models. The 2.2V K6 model 7 and all later K6(-2/III) models are not supported.

If your K6-233 is a 3.2V model 6, it is supported by the BIOS. But the BIOS also contains an Apple Compatibility BIOS v1.6.4 module that may prevent other than the original Pentium from running.
Although I’m just guessing here, it would be interesting to see if a Pentium MMX, Cx686MX, or AMD K5 work on this card. If you have one of these CPUs, please try.

Another issue may be the power supply. The K6-233 draws a lot more current than a Pentium 166/200. If you can lower the multiplier, you could test the K6-233 at 200 or 166MHz. At these speeds, this CPU will run fine at a lower 2.9V Vcore.

Now to answer your question, with basic K6 support it should be possible to add K6-2 support to this BIOS. But this is a lot of work, so please try the above CPU alternates first, so I know that the time spent on patching this BIOS is not waisted. 😉

Cheers, Jan

Jan, I have finally gotten around to testing the K6-233 again with an externally powered voltage adapter and I'm pleased to report that it worked! So it does appear that the K6 was just a little too power hungry for the built-in regulator. I also realized that I gave you the modded BIOS file (BIOS9.ROM) which I had attempted to replace the VBIOS module using amibcp. It is likely best to start any CPU additions on the base BIOS and I should be able to easily add my VBIOS and second cache bank mods on top of that if it works. The original BIOS I have attached here (BIOS 8.bios) is the file exactly as I extracted it from the Mac application.

Sphere478 wrote on 2025-10-28, 02:52:

If there was PCI I would say to try to make an adapter to a radeon 9250. But with ISA, the onboard would be better.

You may be able to boge wire attach a breakout for pci still though if you tap into enough of the legs, pins, and traces.

The data book for the chipset is archived at the retro web: https://theretroweb.com/chipset/documentation … b7863333286.pdf. According to it, the PCI signals come from the 82C557M and 82C558M chips and are mostly isolated to one corner of each. I'm thinking something like one of those "quick solder" FPC boards I've seen in console modding kits could be an option to quickly tap off those signals and send them somewhere else. A PCI to PCI adapter card could then be designed to get power from the Mac's PCI bus and the rest of the lines from the FPC. It would only allow for low-profile cards, but it should work... Excessive? Maybe. But possible, almost certainly.

This card has kept me busier than any piece of retro gear I've had before!

Yes, you and I are on the same page with that idea. I had the exact same concept, churning around in my brain

I think some of the PCI configuration though might be in the bios so some bios mods may also be required

Sphere478 wrote on 2025-11-02, 02:02:

I think some of the PCI configuration though might be in the bios so some bios mods may also be required

Thankfully, amibcp works on this BIOS and allows access to most of the registers and embedded device configurations. I have a third mod going where I'm attempting to stack cache chips to give a dedicated dirty bit and two banks for a total of 512k of L2 cache. The default configuration has combined dirty and tag bits with a single bank for 256k of cache. It is hard coded to write-back and the chipset only supports 32MB of cache-able memory in that configuration. The cards support up to 80MB of RAM though, which I should be able to have all cache-able if the mod succeeds. I hope to try even faster chips and see if timings can be improved too. I was able to easily compare the registers in the databook with their configurations using amibcp; which is especially nice because getting into a BIOS menu doesn't seem possible on these cards, much less saving the configuration.

Hi Jan,

I got a EPOX EP-MPV3G-M mainboard, and you have a modded BIOS for it on your homepage. The BIOS image on your homepage is 256KB (2MBit), but the chip on the board is a 1MBit chip. I happen to have a Winbond 49F002U-15B flash chip I currently don't need, so I decided to use it. I successfully hot-swap-flashed it inside that board, and now the board recognizes an AMD K6-2+ perfectly, which it didn't do with the vendor BIOS.

There still is an issue, though: While the AWDFLASH version in the archive on your homepage does support the Winbond 49F002U, the ESCD updating code in the BIOS image does not. Instead of "Updating ESCD", the BIOS shows the error message "unknown flash type". Can you easily prepare a patch to support this chip (possibly instead of another 2MBit chip)? If not, I'm going to try to prepare that patch myself.

Helpful Info about the W49F002U:

• Enter read ID mode: AA/55/90 to usual magic addresses
• Exit read ID mode: AA/55/F0 or just F0 written anywhere
• ID: manufacturer code (at 0) = DA , product code (at 1) = 0B
• Sector erase: AA/55/80 followed by AA/55/30 (can be used to erase the parameter blocks, which will be at F000:8000-A000 and F000:A000-C000
• Byte program: AA/55/A0

I assume that the code required to access a flash chip with these parameters is already present in the ROM (these are the codes recommended by JEDEC), it's just missing support for the vendor/product ID pair.

Thanks in advance for any information!

mkarcher wrote on 2025-11-06, 19:31:

Hi Jan, […]
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Hi Jan,

I got a EPOX EP-MPV3G-M mainboard, and you have a modded BIOS for it on your homepage. The BIOS image on your homepage is 256KB (2MBit), but the chip on the board is a 1MBit chip. I happen to have a Winbond 49F002U-15B flash chip I currently don't need, so I decided to use it. I successfully hot-swap-flashed it inside that board, and now the board recognizes an AMD K6-2+ perfectly, which it didn't do with the vendor BIOS.

There still is an issue, though: While the AWDFLASH version in the archive on your homepage does support the Winbond 49F002U, the ESCD updating code in the BIOS image does not. Instead of "Updating ESCD", the BIOS shows the error message "unknown flash type". Can you easily prepare a patch to support this chip (possibly instead of another 2MBit chip)? If not, I'm going to try to prepare that patch myself.

Helpful Info about the W49F002U:

• Enter read ID mode: AA/55/90 to usual magic addresses
• Exit read ID mode: AA/55/F0 or just F0 written anywhere
• ID: manufacturer code (at 0) = DA , product code (at 1) = 0B
• Sector erase: AA/55/80 followed by AA/55/30 (can be used to erase the parameter blocks, which will be at F000:8000-A000 and F000:A000-C000
• Byte program: AA/55/A0

I assume that the code required to access a flash chip with these parameters is already present in the ROM (these are the codes recommended by JEDEC), it's just missing support for the vendor/product ID pair.

Thanks in advance for any information!

Hi mkarcher,

I’ve read your patch request for the EP-MVP3G-M BIOS and yes, I can do that change.
Thanks for the detailed info about the W49F002U chip.

I already found the flash chip detection routines in the AWARDEXT.ROM module. There are even 4 different detection methods present, two different JEDEC types, one Intel, and one Macronix. These detection routines all work with hard coded values, so no nice table to edit here. 😉

The JEDEC detection type that fits the Winbond chip has values for a seldom used Mutsubishi chip, so I probably will use that for the W49F002U.
I expect to have time to do this change tomorrow afternoon. When ready, I will send the patched BIOS via PM.

Regards, Jan

Hello. I am in the process of porting award bios 6.0 instead ami bios on a PCCHIPS mainboard with SiS630 chipset. I tested 20 bioses with XGEcu, then found a very good one: all on-chip resources are working but the PCI slots are not. I had already modified the $PIR table and I think is OK, but there is no method to re-insert the decompressed and edited bios back to the compressed one, because AWDBEDIT does not recognize the structure. MODBIN cannot work, CBROM can't replace Sytem bios section either, so what can I do just to modify that small table?!

The old bios does not fully initialize the chipset (PCI transfer 12M/s, MemRead 160M/s) and the new BIOS is already great (PCI 62M/s, MEM 504M/s), but I need PCIs for a better video card and USB2.0. It is a shame to quit just because of re-insertion. Can you help me, please?!

I tried to post the ZIP files but it seems that "submit" is disabled when I add an atachement, maybe I am not allowed to add files.

aleodan wrote on 2025-11-15, 08:34:

I tried to post the ZIP files but it seems that "submit" is disabled when I add an atachement, maybe I am not allowed to add files.

You need to choose a license for your attachment before the submit button gets enabled.

What I have done so far:

- Non-original BIOS does work with all peripherals integrated in the chipset, except when sound is active, modem becames inactive (I think is from PCI routing tables too); both PCI slots are not working;
- AwardBiosEditor does recognize the BIOS, but after alteration and flashing computrer beeps continuously and display "BIOS checksum error";
- Modbin6 and Cbrom are not showing any errors;
- It is interesting that the $PIR table is somehow duplicated, because it must be altered again in AWDBEDIT and Modbin shows only what AWDBEDIT changed, not the table altered in ORIGINAL.BIN;
- AwardMod does extract all components and re-assembles them back but with the same BIOS checksum error.
- AWDHACK is not working with MODBIN6.

The board was brand-new, sealed and untouched, but very-very expensive and it did have some bulged capacitors due to its age, so I changed them all; it is unusable with the original bios because it was built for SiS5600 and doesn't initialize any new features; before I had a Jetway board with SiS 620 and broken traces which worked way better after some soldering because it had an Award speciphic BIOS, but it finally died; the new board with SiS630 is way faster, but only with the ported BIOS and I cannot use my Quadro NVS 280 PCI card and USB 2.0 controller which I used with the old board.

Any suggestion, please ?!

I also tested the AwardBiosEditor by loading the partially working Award bios, then I save it unmodified; after flashing the same "BIOS checksum error" appears. It seems that the AWDBEDIT is corrupting the version 6.00 bioses somehow.

Then I tried to load the modified bios into Modbin6 for DOS and for Windows, modified the initial string and saved it in hope that the checksums will be re-calculated, but with no sucess...
Please help !

Decompressed system bios seems to have 2 checksum bytes at the end. AwardBios Editor says that 6.0 bioses have no checksum and corrupt it. Maybe the two bytes from the end are CRC-16, or something.
I have tried to compare re-calculated checksums and CRC-16 in the unmodified decompressed bios by using HxD, but none of them matches the bytes stored there: FC 10. I need to know where the bytes are, what sections and what method was used.

Hi aleodan,

I’ve read your messages about porting an Award BIOS on your PCChips board with an AMI BIOS. From your original 09/25/2001S AMI BIOS, I see that this is for a PCChips M755LMR V5.5/V5.7 board. Is that your board?

Anyway, I will try to help you getting the modded SYSBIOS.BIN into the compressed Award BIN, with all the correct checksums.
I’ve done this many times on the compressed Award v4.5xPG BIOS, but never on a v6.00PG. So it will take me some time to analyze the v6.00PG BIOS structure and how the various checksums are calculated.

Greetings, Jan

Thank you for response !

Yes, that't my board, but version 7.1:
https://theretroweb.com/motherboards/s/pcchips-m755lmr-v7-1

In the mid-time I had figured out why AWDBEDIT is corrupting 6.0 bioses !!

There is a checksum for the decompressor block at address: 37FFFF which inbcludes the checksum of the entire block before it at address 37FFFE. Well, the AWDBEDIT probably usese some C implementation bug with signed "char" instead of "unsigned cher" and looses the bit7 from this checksum at 37FFFF.

Noy I can alter the BIOS the way I want by hex edit that checksum ! It must be good news for anyone using AWDBEDIT to mod bioses !! No more checksum errors and the moded bios boots fine.

BUT: It seems that I have done some mistakes in the PCI IRQ routing table because tthe board reassigns the IRQ, but PCI slots are not working ...

Sorry, the checksum with missin bit7 is at the address: 37FFF. Only three Fs, I am in hurry now...

Sorry for my typo-s. It seems that Award Bios Editor can be used now and there is no need to manually calculate checksums.
The problem now is that there are two instances of PCI IRQ routing table (probably one in the main system bios and the other in acpi table).
I had modified both of them wrong. It seems I have nissidentified some slot entries or there is more to be done for porting than onlky altering IRQs.
Can you help me with a suggestion?

The bug from AWDBEDIT is very consistent: it always looses the bit7 of the checksum of the decompression block from the 37000-37FFE which is stored in the 37FFF location.
Tested five times with different bioses v6.00.

So, now we all can modify Award Bioses 6.00pg with Award Bios Editor by recalculating that checksum in any hex editor.

But, there seems to be something more to do or I don't know what to write in the IRQ field, I only modified the INTA, INTB, INTC, INTD sections.
The PCI video card is detected, receives IRQ (that was also the case with unmodified ported bios) and works perfectly in DOS, but in Windows it displays only some weird rectangles, then freezes.
With original non-ported bios all works ok, but at 486b level-speed, especially in DOS.

What do you think about this ?

For the moment I dont't really understood what IRQ field from AWDBEDIT means. It has no corresponding field in AMI bios edited with BCP7B12...

I need help to for correlation of PCI routing tables. I didn't get anywhere with just trying combinations...
Award Bios Editor is good for changing any Award v6.00pg bioses and needs only the inversion of bit7 of the decompressor checksum at address 37FFFh (XOR with 80h) from 256k bios using an hex editor.

I am attaching my PCI routing tables from both bioses in hope someone can give me any suggestion: