Maybe a real EEPROM chip but probably the wrong one. The VT6421A needs an LPC-EEPROM. I have a VT6421A myself, and it had a wrong chip soldered. It worked after i desoldered the chip and used the right one.

https://www-dosforum-de.translate.goog/viewto … n&_x_tr_hl=auto

hth

luRaichu wrote on 2025-05-27, 18:02:

I bought this SATA+IDE controller card for my Biostar MB-8500TTD which has the 430TX chipset. It's PCI 2.1 only and the VT6421A […]
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I bought this SATA+IDE controller card for my Biostar MB-8500TTD which has the 430TX chipset. It's PCI 2.1 only and the VT6421A uses PCI 2.2 according to its datasheet.
The BIOS detects it as a "Mass storage device" on IRQ 11, but it will not boot from an IDE CD-ROM drive attached to the card.
I tried to flash the Memphis ROM to it with the provided DOS program but it couldn't detect the ROM chip type...
Then I plugged the card into a newer ATX PC running Linux and it showed up as a RAID controller. I could mount attached SATA drives. But when I tried to read or write the card's ROM with flashrom it kept saying it couldn't find a compatible PCI device even though the card ID from lspci matches up with other cards that others flashed successfully.
I'm pretty sure the EEPROM chip is real? Some of these cards are sold with a fake ROM covered by a sticker.

It is normal for them to not be able to boot from CD, and also for the CD rom to not be detected under DOS. Not 100% sure about that card in particular, but my promise IDE cards are like that.

If I use them usually I just leave a cable attached to one of the motherboards ide plugs and use that for windows installation/ any dos benchmarks etc I may want to run from a CD. I suppose a more elegant approach could be just having a second drive for this purpose but meh

XCDROM and the other ATAPI CDROM drivers in FreeDOS can sometimes find PATA/SATA CDROM drives on nonstandard I/O ports by looking through PCI configuration space for them

Here is what my card looks like.

luRaichu wrote on 2025-05-27, 23:42:

Here is what my card looks like.

I bought the same card last week, to use it as a programmer to flash a bricked Socket 754 mainboard. At the beginning I had same problems.

First, you need a 32-bit Linux installation to let Flashrom recognize this card. I tried on Debian 11 amd64 on a Gigabyte 8I865GME-775-RH with ICH5 southbridge, this card showed up in lspci but same "can't find a compatible PCI device" error. Then I tried it on a G41 mobo with ICH7 southbridge and Debian 11 i686, the error changed to "no supported EEPROM was found". I switched to verbose mode, now the card is properly detected by Flashrom.

Second, you need to remove two resistors (R39 and R40, located near the lower-left of the ROM chip) to get the ROM detected. R37 to R40 determine the address of corresponding ROM chips to let up to 16 chips connected to the same LPC bus. As we only have one chip it should be 0000 (R39 and R40 populated = pulled high = 1100). After that, the ROM get recognized.

Third, this particular model of ROM (SST49LF004B) is not supported by Flashrom with atavia programmer. I replaced it with a SST49LF040 and it worked. You can modify the source to add support for 004B, but it might not work as it's a FWH mode chip (a variant of LPC by Intel) instead of "pure" LPC like the 040.

Thank you for this information.
I removed R39 and R40, but the WR6421 program for DOS says that the LPC flash VID/DID (Vendor ID/Device ID) is FFh/FFh and it's Unknown. That's probably the same error I was getting earlier.
Also, this card uses the same EEPROM as mine. https://theretroweb.com/expansioncards/s/gemb … to-sata-and-ide

I ran flashrom from i686 Debian 11 Live but it still isn't finding my card. Maybe it can't access the PCI bus? This is on a Dell Inspiron 530 which has an Intel G33 chipset.

I will try replacing the ROM with an SST49LF040

My SST49LF040 arrived and I installed it on the VT6421A, but no luck flashing it on Linux or DOS. I may have done some Bad Things while soldering.
Next, I tried to add the (64K) Memphis ROM to my Award BIOS using CBROM. But it seems there is no room for it (only 32K free). Is there a way to squeeze it in?
If not, I must use an option ROM on an Ethernet NIC to boot. I have a Macronix MX98715 based card, it's a clone of the DEC "Tulip" chip. I don't own an EEPROM programmer so I would rather use this card to program the option ROM. There is a patch for flashrom on Linux to read/write ROMs on DEC Tulip cards.