PcChips was notorious for putting their own markings on many of the eeproms of 486 thru pentiums.
Are you sure the new bios files you have are correct ?
According to TheRetroWeb board is same as Amptron 9100A and the 2002 webpage: https://web.archive.org/web/20021017211904fw_ … l/biosCode.html
where it states " PM-9100A M571 3.2 04/21/1999 NOTE: This is a 1Mb BIOS file."
The BIOS Update there includes a BIOS flasher and BIOS dated 4/1999, and is attached below.
Note: hex edit of the Amptron bios shows: 007_66_M571......[...07/15/95 same as the BIOS downloaded from https://theretroweb.com/motherboards/s/pcchip … 3.2-a#downloads
You can either flash the bios in package below OR use the BIOS flasher and flash the bios you got else where BUT if it a modded bios it may not want to flash anyway and you need a programmer....
Do not change the eeprom voltage selection <from the manual> !! fixed error ;p

added: the attached perfectly hex matches this: http://web.archive.org/web/19991117082532fw_/ … om/m571b32.html
"5710421s.bin checksum: * FEA4 * (<== ** the new bios file **) , BIOS code: AMI BIOS , BIOS code: Releas 04/21/1999 S"

Few updates,

I got a working floppy and booted into dos from the floppy disk. Using AMIFL632 I was able to get it to finally show flash information. It lists the flash as SST 29EE010. I attempted to use AMIFL632 and it failed to flash (does not seem to have really attempted). I then tried uniflash 1.4 with the SST29ee010 forced as it still did not detect and that failed writing to almost half the blocks. Rewrote the backup firmware successfully, verified and rebooted without issue. I did this for both the firmware you listed and the factory firmware I found, same result both times.

With the boot floppy I have also tried aminf332, aminf329 and aminfm326(this was in the package you listed) and all give the error "Chipset/Flash part isn't available/ The function will be invalid".

I saw links to another app called flashrom that seems popular and supports this chipset, but the dos binary download seems down and I am not going to cross compile it on a hunch.

Did you find your way here yet? http://m571.com/m571/index.htm

A thing I noticed in the past about PC chips boards is that they were maybe using reclaimed EEPROMs as many seemed to "run out" of rewrites after a small handful of tries, where the flash tech of the time should have permitted 100 or so.

It has recently been discovered that tired flash cells can be rejuvenated by a period of elevated temperatures. Unfortunately that's not well dialled in yet for home meddlers.

Double-check that you're flashing the correct BIOS for your board revision (3.2).

Note that BIOS images created for later revisions might not be compatible with your motherboard.

I do not think this is a bios compatibility issue. I have poured over the two fan pages for this board and looking back at them again, it seems that the bioses are completely compatible from the 3.2 to the 3.2a. All of the links put them in the same sections. The 3.2 and 3.2a are also 99.9% the same board with the only difference being the ability of the 3.2a to go down to 2.2v core voltage vs the 3.2 capping out at 2.5v. There is even a later model of the same board with fewer expansion slots that can be cross flashed.

For the eeprom, pulling up the datasheet this seems to be a fairly good chip. It does indeed run at 5V with the write endurance being up to the 100,000 range. One thing I noticed is that the datasheet mentions a Software Data Protection that must be disabled with a byte sequence before writing. This seems to correspond with the message I am getting in uniflash. It would also explain why flashing stops immediately when attempting with that standard AMI flash apps. For now I am not even certain that uniflash was writing anything.

"The SST29EE/LE/VE010 provide the JEDEC approved optional Software Data Protection scheme for all data alteration operations, i.e., Write and Chip-Erase. With this scheme, any Write operation requires the inclusion of a series of three byte load operations to precede the data loading operation. The three byte-load sequence is used to initiate the Write cycle, providing optimal protection from inadvertent write operations, e.g., during the system powerup or power-down. The
ST29EE/LE/VE010 are shipped with the Software Data Protection disabled. The software protection scheme can be enabled by applying a three-byte sequence to the device, during a pageload cycle (Figures 5 and 6). The device will then be automatically set into the data protect mode. Any subsequent Write operation will require the preceding three-byte sequence."

I have somewhat given up on flashing this eeprom from the board. There is nothing in the bios for SDP and there is no way I have found to disable it to allow for a flash. I don't have an eeprom flasher and don't really need one for other uses. So for now I just need a flashed eeprom chip. I was looking at a site that offers burning services for any bought chips, but the shipping is $9 on a $2 eeprom and it is 9-20 days shipping time. Does anyone have suggestions on services that might be faster or cheaper?

where do you live ? And what is the current BIOS version on your board ?

Bios is dated 2/24/1998 (s), I am currently trying to update to the latest official bios dated 5/14/1999 so that I can at least get support for the K6-2. A K6-2 475 currently shows as AMD Unknown and hard locks if trying to boot (even at a much lower frequency).

I am in Texas but having trouble finding a supplier that is stateside.

Ahh ok. If you were an Oregonian would flash it for you free if lived in my state and you paid mail.
Other issue is that your eeprom might have a write defect which even my TL866 II Plus cannot fix...

I found another vintage forum post describing the need for a bios update on the M571 to support K6-2 processors (unknown AMD and then freezing at post). So convinced this will fix my issue, I bit the bullet and ordered a 2nd SST29EE010 with the latest bios file on it. I went ahead with the hacked bios that supports K6-2+ and K6-3+ as other users on this forum have had good luck with it. Should be here in the beginning of next month. Fingers crossed. I will update when it comes in.

An update to everyone, I got the replacement SST29EE010 in with the new bios flashed on it. It seems like exact drop in replacement. It shows version 05/14/1999S - Patch J.1 on boot and recognizes the K6-2 without issue. Even got it maxed out for the board running at 500 Mhz (83Mhz X 6), just a little over the max rated 475Mhz of the 2.4V K6-2 variant that I am running. I am just thrilled.

As for the prior EEPROM, something I noticed on boot is that it always tried to write to the NVRAM and failed. This EEPRom/Bios can write to the NVRAM successfully on boot. Whatever they did on this original EEPROM, I am starting to think it is some kind of bootleg chip situation. Between the inability to write with any application and the crude eeprom markings it just doesn't add up.