First post, by JidaiGeki
I've got a few builds in the pipeline, but this one is tickling my fancy at the moment. To kick off, here's a pic of roughly where I'm at:
I've never owned a full 386DX until now, as my 386 machines have otherwise ended up being SXs. Friends in the past had computers based on 32-bit 386s, but at home I skipped from an SX desktop straight to a Pentium, with only brief dalliances with cut-down 486s in laptops. So this is a bit novel, but it does fit nicely into my line-up.
This build didn't start out with a 386 focus. I bought the desktop case a couple of years ago as it was affordable, and I wanted to house a 486 motherboard with a DX4-100. Archmont was from memory just a vendor of re-badged clones here in Oz (not that that is a bad thing, of course). This is how it was when I first got it, it was mostly an empty shell with an Ahead ISA video card screwed in to the rear cage.
Though it didn't come with a motherboard, the quality check date on the PSU and other bits suggested an original build of late 1991. The guy who sold it to me mentioned that it was a 386-based machine, before the barrel of death leaked and killed the motherboard, and corroded part of the case.
I sort of fixed it up, sanding back some surface rust, and taping off and spraying the worst area inside and out. I couldn't match the bare metal finish of the case interior, and spraying the whole thing would be a waste of paint & time. Ultimately it's covered up by the motherboard so the repair area doesn't bother me.
The origins of the motherboard are a mystery to me, I can't remember how or when I bought it, or who the seller was. Probably a spontaneous late night eBay purchase. Anyway, it has a ULSI 387 co-pro, and came with 8MB RAM installed. The problem was, half of it was parity, the other half non-parity. It wouldn't boot with all 8MB on-board, so the parity RAM has got the chop for the time being, and it got into full swing with 4MB. Maybe I'll consider 32MB next year, but it'll probably need all parity RAM then. The barrel battery is removed, and there isn't a replacement organised as yet.
The power supply arrangement is temporary; after some digging I found the proper power switch but to fit it means taking off the case front again, so for now the ultra safe arrangement is to have the switch dangling over the front. Cards that are going into it are a Tseng Labs ET4000 (with "Rainbow" BIOS); a Winbond floppy and IDE controller; an Adaptec SCSI/sound card (AMM1570); and possibly some other sound card to complement the Adaptec, maybe a GUS or SB depending on how the Adaptec sounds. The AMM1570's supposedly got on-board wavetable, but having read the two manuals for the card twice over I'm guessing that's only available in Windows as it's not mentioned much at all.
The LED MHz display almost deserves a post to itself. Given that this was going to be a 486 build, I originally swapped out the 2-digit LED display, and put in a 3-digit display, which lined up perfectly with the aperture and screw holes and had standard jumper settings. Once I decided to go back to the 386, the 2-digit unit was more appropriate, so it was restored to its rightful place. Originally, I'd had a hard time figuring out how the 2-digit readout, an "AT-05C" model, worked. There are no instructions anywhere online. It has two banks of DIP switches, one row for tens, and the other for units.
It wasn't immediately apparent to me how this worked, and only through logging various combinations did it become clear what was happening. The bank of 7 is for tens, the bank of 12 is for units. The switches for units seem to map roughly to the segments (theoretically it should have 14 switches, but it's working now, so no need to touch it again soon), while the switches for the tens (the bank of 7 switches) light up different combinations of segments that can be pieced together to make legible numbers. For the non-turbo mode, only the first three switches changed anything, giving readouts of 1, 2, 3 or blank. The non-turbo display range can only range between 1 to 39.
Close enough wasn't good enough. The stray single black lead shown in a previous pic, when plugged into the motherboard's +ve turbo LED terminal, activated the Turbo mode. This then opened up the balance of the switches to give a greater range of displays. I haven't tested all combos but I'd imagine 99 is possible. I've set it at 40 now, and hooked up the Power and Turbo lights which are powerful enough to shine through the smoked plastic cover as shown.
So where I'm up to is planning the next phase. The case seems to be a little out of square, so fitting drives and the blank drive cover is a physical challenge. The original power supply died on me but there are some on order. While I'd love an era correct monitor, I don't have one but my eyes are still peeled for that elusive 14" CRT. Finally, I've got a Seagate Hawk 1GB drive to go in, and the CD-ROM installed in the first pic is a 4x SCSI caddy loading Toshiba XM-3501B. Once those are hooked up, it'll be DOS 5 or 6.xx with Windows 3.11 on-board, and then it's DOOM time.
Thanks for looking, I'll try to update soon!