I wasn't having trouble remembering.
*Any* such daughtercard, practically speaking, will fit, presuming that it's not the size of a Dell Pentium 4 heatsink. There's a good couple of cm clearance there, not the least because, while the BIOS *setup utility* for the system is on a Compaq "Diagnostics" floppy of all places, rather than being resident in ROM, the actual configuration information is stored in the back end of a DS1287 or DS1287+ chip, socketed down. This is actually a bit of a dirty secret here -- I need to go in and rig a coin cell to that daft little chip to make it work again, and then make and use the floppy disk (I have the image, I just need to write it to a disk and boot into it) before it will boot properly. Great work, Compaq, I wish you'd spent that extra quarter on a ROM chip -- being that this is the third generation such machine, I'd think you could afford it by then...!
Before you go off crying "So you don't even know if it works?!" -- I have verified that it powers on and at least *tries* to find an OS, just that the BIOS needs resetting. This one has a dinky 3.5in hard drive -- a Connor somethingorother, I forget the capacity, but I'm almost certain it's on the order of 40-something megs -- that sits in a bay adapter, and the absolutely shortest 5.25in floppy drive I've ever seen, I swear it's almost square! in a little dual-disk 525in caddy that slides into a slightly bigger cage on the side. If it turns out later that booting anything of significance gives it heartburn somewhere, the kind fellow who shipped me this thing from an adjacent state (not even kidding! and I didn't pay a penny... thanks, dude, I owe you big time -- you know who you are 😉 ) also included a parts machine that has everything but the drives and the caddy they sit in inside the cage.
These are the 'lunchbox' form-factor luggable Compaqs, and through luck and fortune, I actually have the ability to bodge together an absolutely disastrous kludge of a 386-box version of this if I actually wanted to -- but we're talking absolute "kiiiiill meee" level 'engineering' here. I have a 386 motherboard that will fit -- an American Digicom P9-H -- it will just *barely* wedge in, if I remove the drive-caddy cage and the other internal partitioning. Another Internet friend, two states away, some years prior, sent me a Toshiba 486 laptop, a Portege T3400CT, but there's something goofed up on the motherboard (it actually has 'color RAM' like a C64, and I suspect that that's gone bad, it looks a little suspicious -- BTW, yes, I managed to locate a replacement LCD panel, that isn't it -- nor is it the cable in between) and it took me buying up *three* *more* *machines* before I got a working system out of it all. So I have a working 486 Toshiba that looks a bit like if an ASUS netbook wound up on that "My 600lb Life" TV show... and three machines' worth of parts that can't be combined into anything useful because the only motherboard that boots properly is too addled to properly comprehend color any more. But the LCDs are base-VGA spec (640x480 / 8bit color) and I have a few to spare now -- and they'll fit the Compaq's screen housing quite handily... 😉 it's just that the datasheet no longer exists, so getting the pinout means spending an afternoon with a multimeter set on continuity, playing Aliens vs Paris Hilton with the cable assembly... nowhere near as much, er, fun when you realize that there's two connectors on the LCD side, and the mobo uses a 40pin Hirose "LVDS" connector -- and the inverter is hung off the same cable as well, so there's like four different connectors being juggled about at once here, one on one end and three on the other... so I guess it's more like Captain Kirk and that cat-girl at the beginning of "Star Trek V" then... and we all know how *that* ended! Yikes. Buuut that particular mobo has eight ISA slots, and only the bottom two are ISA-8, so there's plenty of room for things to make noise and sound and run drives and all that... I might even be able to bodge in a CD-ROM drive if I can make a big enough beige wart on the back for it... or just run a really long cable out of a slot cover (probably it'll be that)... and I have a universal VGA-to-LVDS LCD driver board, one of the ones you use jumpers to set, I can use that off the VGA card... yay...
...or, I could just stick an accelerator daughterboard in the system that I know *already works pending a BIOS de-stupiding* and run a few bodge wires to whatever it needs that the processor socket doesn't serve up.
