First post, by ralphmaif
It started here...
I failed (miserably) at working with QFP 100pin de/soldering (a story for another beer) and had started looking for socketed 386DX boards and systems so I could scratch that itch of taking a 386 to a 486 like I did as a kid. This came up...
Mitsubishi MP 386s. It's an Intel 80386sx-16 with an Intel FPU, 1MB (or is it 2MB?) onboard RAM, and no hard drive or video controller despite a floppy controller and plenty of ports (AT keyboard, 2x db9 serial, and parallel). This one arrived at my house with an ISA IDE card, an ATI LMS audio card, a WSS sound card, yet no video card. I couldn't find much detail on it other than there were some proprietary parts which do end up limiting its capabilities when unavailable.
But a socket is a socket.
The TI486SXLC2 G50 WN is technically 3.3v but 5v tolerant. My crap desoldering was able to facilitate swapping the 32MHz crystal with an oscillator socket for which I've tried both 40 and 50MHz crystals. I also replaced the Intel 80387 with a Cyrix FasMath.
The challenge is this...
I think this is the header for a proprietary RAM module that is basically unobtanium now. Worse yet, that's your only path to 32bit memory upgrades as there are no slots of any spec on this board. I picked up an Acculogic RAMpAT! Plus which, even loaded up with 16MB 60ns of parity memory, doesn't compete when choked on an ISA bus.
But I'm having fun. I got a Powergraph x24 1MB board, a Sound Blaster 32 CT3600, slid a 32x CD drive where the 5.25" floppy was, hung a 2GB CF card off the controller, and boot to DOS 6.22, courtesy XT IDE ROM on the 3c509b.
Games like Tie Fighter and Doom, of course, run like ass when trying to hammer extended memory, but Wing Commander 1 and 2 are brilliant.
I still need to sort out issues like the RAMpAT's dead battery, dialing in the best Cyrix utility for L1 cache and clock doubling, and dealing with the checksum error on the CMOS. That last one is a head scratcher. I replaced the battery, so the date/time memory works, but there's an error at boot up and no native way to get into the BIOS at POST. I found a couple generic Phoenix utilities that run from DOS to allow some editing, but neither clear the error.
Will keep searching and will post more photos later. It's really a nicely constructed beast.
