Sadly not. The SCSI card still won't work in Podule Slot 0 (fails the Powertec SCSI POST, with no details on what's wrong) but works in the other three.Did that fix your SCSI podule issue?I just removed the two PALs and one of them (IC3) had a crack in the package and a rotten track underneath it. No wonder it was misbehaving.
BTW, the PAL functionality is also mentioned in the A540/R260 TRM, page 1-7 where it shows the mask register is &3360004 and the request register is at &3360000
I've tried an ANT Ether3 in all four slots and it's happy -- so clearly my recreation PAL works as Ether3 will fail its selftests if Podule interrupts aren't working. Pulling the PALs is enough to prove that.
I'm thinking there might be a bit of grot or a short under slot 0. The other possibility I'm looking at is the SCSI card is a MEMC or MEMC+IOC podule, and the MEMC side of things isn't working on that slot. But IORQ/IOGT buzz through to the other slots fine...
The 74HC139 is a suspect, I've got replacements on order.
The broken PIRQ track between the backplane plug and the PAL outputs turned out to be under IC3 (the cracked PAL). The solder was crusty and awful on that one so the rot clearly went a long way. I've fixed the track properly and removed the jumper I'd originally fitted.
I've attached the WinCUPL II PLD files for the 0283,041-03 IRQ mask PAL recreation, including test vectors.
Statistics: Posted by philpem — Thu Nov 27, 2025 8:48 pm