B Degnan wrote: You have most of the components of a TM990 system. This was TI's attempt to market the 9900 to developers, mostly for embedded systems, industrial controls, and so forth. TI seems to have fumbled the the late '70s microcomputer market in this case, as well with the 99/4, but not due to any fault of the TM990. For whatever reason, though, most here will be far more familiar S-100 micros, and with Intel, Moto, Zilog, and other development systems, excepting maybe the TM990/189 type single-board trainers which are fairly well known. You could get a full TM990 software development system, though, eg. the TM990/602. There any number of tools and languages available for it, including UCSD Pascal. The only reference I ever saw in the microcompter press about TM990 systems was a couple of articles in the Feb. '83 99er mag by David G. Brader, about the aforesaid TM990/602 and UCSD Pascal. I contacted Brader not too long ago on the off chance, btw, but he says the system is long gone. TM990 systems live on in the industrial automation and control world, as TI used them heavily in-house. I've mentioned before here the VPU200 programmers for TI sequencers and PLC's are TM990 based. (They have a 7-slot backplane, btw.) Seimens, which bought the TI industrial controls business, still lists parts for them in their catalogs, so many if not most industrial automation supply houses will still have parts, though not at hobbyist prices. (This is one case where ebay is definitely your friend, though. I picked up a TM990/311 buffered I/O board for cheap there.) I'm working on a VPU200 right now which has what looks like a 101MA processor board, 64Kw RAM board (pn. I'm not sure of), Floppy controller, pn. undetermined. and a 5TI sequencer interface port, pn. undetermined. (These boards don't have the TM990 numbers on them, just the regular TI pn.s. So far I haven't found an xref.) Luckily I have the "OS" (actually just an executive, a few utilities, and the programming app.)for it (5TI, 6MT, and PM550 versions), and it looks like TX990 underneath the hood, so I may be able to get some other TX990 apps running on it. This particular VPU200 has one 360K 5-1/4" floppy. The TM990/602 had IIRC an FD800 or FD1000 dual floppy setup. The VPU200 has a CRT and keyboard as part of the case, the /602 uses a serial terminal. The 4-slot card cage and backplane is a TM990/510. With power supply, TM990/522. That may help you if you try to get yours running. There were plenty of other TM990 boards. Bubble memory, A/D, D/A, I/O, extra-hi-density (3.0M, 5-1/4") floppy, GPIB, TIWAY host, comm, something called "MUX CPU", speech synth, different memory boards. Don't know about hard disks or scsi, but that proto board looks like just the thing for constructing an IDE interface. Yours looks like some kind of timer/counter or signal generator of some kind. There is at least one other 100-contiguous-pin bus TI used, in the DS990/1 computer/771 terminal. The form factor is different, having only one card ejector on the left end, front-facing, with a larger board extent on the right end, front-facing. The actual bus may be similar or the same, but I can't say at the moment. Will post some pics, manuals soon, though. Promise. jbdigriz