[kubatyszko]

The two PROM chips could well be the CPU PROM and IO PROM. On IP27, the CPU PROMs were on the nodeboards and the IO PROM on the IO6/IO6G. On a Fuel they are both on the mainboard but architecturally it's close to IP27 so they may simply have kept the dual chips.

This was my exact thinking in formulating my response. But I wasn't sure if architectures like the Tezro might have one chip on the IO9 controller and the other chip on the main board. Obviously Fuel is a single board device in that regard, but same family so same overall component needs during design. So my brain was leading me there.

The programming output from the flash command does talk about programming the bedrock, so perhaps one of them is the programming for the bedrock?

But that being said, I think the concept might hold water. After all, we're talking about recovering a mainboard so as long as it's the same revision, one would think a complete overwrite would still be OK.

I can see a partial rewrite might have compatibility issues or segment update issues, but perhaps a total replacement where everything was chill with the donor might still be a thing. It's definitely going to be on my "look into" list.

Hmm, given that there's just a handful of revisions, all we really need to get this working is a set of "flashable" PROM images for 500Mhz PIMM for every revision.
Then it's all about replacing those 2 or 3 chips on the board with flashed versions.
There are 3 chips, 2 are on top near the PCI slots, labeled "L1 PROM" and "IP35 PROM". The third chip is on the underside, directly below the IP35 PROM - that might be the backup PROM.
This may be even easier - replace only one chip, BACKUP?, with a 500Mhz PIMM version, boot the machine (set which PROM image in L1 , I vaguely recall it was possible) and then use standard flash tool to do the rest of the repair.

Understandably, this is not the same as doing it purely via L1 or CAC commands, and rather invasive (needs soldering), but it's a small price to pay to "unbrick" a motherboard isn't it ?

Cheers