What is the two letter code on that SiS 496 chip right above the copyright year? if it says "PR" it supports EDO, if it says anything else it doesn't.

As far as the board, I don't think it's actually a lucky star. It looks similar but the BIOS, CPU and cache are all in the wrong place.

Looks like OR or QR to me, not PR on the SIS 496.
Ehh it looks identical to Tiido's LuckyStar LS-486E Rev:C layout which the BIOS string comes up as Lucky Star and is same BIOS string except for a few bits.
Not a Rev D by other criteria as it has the SMC I/O not UMC as in Re: LuckyStar LS-486e Rev:D Hardware Upgrade Guide and https://www.elhvb.com/webhq/models/486pci/ls486ed.htm.
So no, probably will not support EDO, and even if you could get it too.... 486 with EDO is not faster then FPM in general so could be a waste of time trying and probably why the AMI bios not the Award.... just my opinion.

maxtherabbit wrote on 2021-08-03, 23:25:

What is the two letter code on that SiS 496 chip right above the copyright year? if it says "PR" it supports EDO, if it says anything else it doesn't.

OK, this makes some sense: The datasheets for the SiS496 chipset I found usually describe EDO support, but I didn't notice any revision dependence in the data sheet. In my experience, no SiS496 boards actually works with EDO RAM, though. The PCI revision register is just described as "The current version of 85C496/497 is 02h". I know it's the same with the UMC8881 chip: Only the latest revision (which happens to be labeled "E" just like "EDO", IIRC) supports EDO RAM.

Do we have a canonical list somewhere on what chipset revisions support EDO?

My FreeTech 486F55 board definitely supports EDO RAM, and the BIOS POST screen even lists "EDO RAM at banks: 0, 1, etc.". The 85C496 is dated "9611" and has the "PR" label next to it.

TheMobRules wrote on 2021-08-04, 08:41:

My FreeTech 486F55 board definitely supports EDO RAM, and the BIOS POST screen even lists "EDO RAM at banks: 0, 1, etc.". The 85C496 is dated "9611" and has the "PR" label next to it.

Thank you for confirming that there are SiS '496 mainboards that do work with EDO RAM! I've not encountered such a board yet. Looking at the date code 9611, this board has been produced at a time where (at least in Germany) the Pentium had mostly taken over the main consumer market already.

I've seen BIOS support for EDO RAM on a lot of '496 boards, yet they generally didn't work with EDO RAM. At first I supposed that EDO RAM would only work if /OE is connected between the chipset and the RAM, which is impossible with PS/2 SIMMs, as /OE is not on the PS/2 slot. Then, after careful examination of the data sheet, I discovered that the EDO support is supposed to work in a non-/OE-dependent way (using a stray /WE pulse, which should work according to many different EDO RAM data sheets), and I queued to re-investigate the EDO-support issue.

Being dependent on chipset revision (and having new BIOS code with EDO support distributed to boards with old chipsets) explains why I saw a lot of EDO-capable 85c496 BIOSes (as you describe - it had the code to print messages like that, and the memory detection routine had the EDO-probing code in it), but none of these boards actually worked with EDO RAMs.

maxtherabbit wrote on 2021-08-03, 23:25:

What is the two letter code on that SiS 496 chip right above the copyright year? if it says "PR" it supports EDO, if it says anything else it doesn't.

the chip says 0R (zero) or OR:
download/file.php?mode=view&id=116080

maxtherabbit wrote on 2021-08-03, 23:25:

As far as the board, I don't think it's actually a lucky star. It looks similar but the BIOS, CPU and cache are all in the wrong place.

The bios string says -001256- that is an Ami code for LuckyStar is it not? See here:
http://lmg-data.dk/Pc/ami.htm
download/file.php?mode=view&id=116081

I have another 486 setup with Abit PB4 and Ali M1489 chipset that runs EDO just fine.
The reason im asking is that i have a bunch of 32MB EDO simms as they are cheap and common.
Its much harder/expensive to find 32MB FPMs. I have only one and it works with the board just fine so i guess i will have to find another 3 to fill the board up 😁

maxtherabbit wrote on 2021-08-03, 23:25:

What is the two letter code on that SiS 496 chip right above the copyright year? if it says "PR" it supports EDO, if it says anything else it doesn't.

As far as the board, I don't think it's actually a lucky star. It looks similar but the BIOS, CPU and cache are all in the wrong place.

Are you sure? Only PR?