Iiiitsss aliiiive! (more or less)
How's this for a Frankenstein:
ECS SL486E EISA / ECS Local Bus motherboard
BusTek BT-747 SCSI/floppy controller
SMC Ether 10/100 NIC
Compaq Advanced VGA
Am5x86 on VRM interposer
Miniscribe 8425S (yes, ancient 21MB 1987-era drive)
This is a build I've been messing around with for literally years. Every damned connector on it was oxidized, so electrical connections were flaky on everything from cards to CPU. The SIMM slots are incorrectly numbered, first bank needs to be filled first, but that's slots 5-6-7-8... however the biggest issue was of course the soldered DS1387. As it's the 1387. I made a bit of a butcher's job of de-soldering it, losing a few pins in the process (damned GND plane soaking all my heat as usual) so after putting in a socket I needed to bodge a prosthetic set of legs onto the module using another socket. Then hacked it open to connect the external battery... it wasn't pretty but it worked. About twice 😦
Because of all the contact issues I wasn't sure the problems were related to the DS1387 - if removed the board definitely didn't even start POST. So ordered a new one and installed it today. Not only did the system boot, it turns out the 21-year old battery still holds power. So I'm back in business.
EISA config was interesting. Little things like the FDD on the BusTek card was disabled by default and the Advanced VGA card claiming it couldn't do any graphical modes (it can, I checked afterwards). The HDD is temporary of course, it's the only 50p SE-SCSI drive I had at hand. I have a huge 535MB full-height 5.25" drive I could use, but it's currently doing cosmetic duty filling a bay in an XT clone, and it's so noisy I don't want to use it anyway. Only alternative I have that's not far too big (or fast - 486 running a Cheetah 10k.7 is even more crazy than an old SCSI-1 20MB drive) is a 1.2GB Seagate ST31200WC pulled from a Sun Sparcstation. Only it's worse than the monster drive, this is the loudest single drive I have ever had. Oh well, once I run out of 20MB I'll choose (or buy) something.
One issue I still need to sort out: keyboard. The keyboard seems to go crazy (registering huge numbers of presses) at random and at pretty much every boot. Press a key and it behaves again for a while. Feels like de-bouncing is also off. Tried three keyboards: same trouble. Tried a different keyboard controller chip: same trouble. Downgraded to 486DX33: same trouble. Weird...