Jed118 wrote:

I burned out my BIOS chip - it was inserted backwards when I put the board into storage ever so long ago - when I went to test s […]
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I burned out my BIOS chip - it was inserted backwards when I put the board into storage ever so long ago - when I went to test some DLC chips on it, it did not post. I only noticed it because my finger touched the top of the EEPROM when I went to disconnect the power leads to the mobo: It burned me!

I tried a bunch of BIOS chips I kept from when I was a kid, and they all emitted some kind of beeps (especially the AWARD BIOS chips) when inserted. Some did nothing, but I know they work (on other AWARD boards) as I had experimented with swapping them into a 3/486 board in the not too distant past.

So, there's a chip on eBay now, same everything (my version is 2.11, but I know 2.10 will work from prior tinkering) EXCEPT it says 386SX BIOS

AFAIK the memory addressing does not happen in the BIOS.

Likelihood of it working? The board is a typical M321, I recently put 256k cache on it.

Failing that, does anyone know where I can get my hands on a replacement?

If you prefer instead, to buy a cheap EPROM programmer and burn your own chip (Probably your best, if not only, practical choice):

http://chukaev.ru54.com/bios_cs_en.htm Look for [3pcm001.zip #] [3pcm002.zip #]

http://minuszerodegrees.net/at_clone_bios/at_clone_bios.htm Look for M321

EPROM Programmer:
https://www.aliexpress.com/item/High-Speed-TL … 0d-4a7b858ceb2c

This is just one example. Search for TL866

I think it depends more on the motherboard than the CPU. A 386SX and 386DX are basically identical functionality-wise.
It's the special chipset features that the BIOS has to support. And a 386SX uses very different chipsets from a 386DX, so I have no idea if the BIOS can work.