TI 990 architecture

James B. DiGriz wrote: Well, something bothered me about this, so I opened the hood (er, bonnet, for our UK list members) of my 990/1 (literally), and it has, in fact, an 86-pin backplane. Oh well, score one for bit rot. Actually, two. I also looked again at one of the VPU200's I have. It has 16Kw, not 64. 4116's, not 4164's. What's interesting about the 990/1 is it has 2 9900 boards in it, one main CPU and the other for file I/O. Thing should zip right along, but that will have to wait until I hook some drives up to it. While I was at it, I opened up an XDS/22 TMS320C25 emulator system I have, since it has an interesting SE9996JD processor along with a 'C25, and it also has an 86-pin backplane, although the pins are split between two card-edge fingers. I have no idea yet if the busses are anything alike beyond that, but the 9996 looks exactly like one of the purple ceramic 9900's, 64-pin DIP and all. Given the nomenclature, I can only speculate that it may be the equivalent of a 9995 without the multiplexing of the data bus. I haven't been able to find a datasheet, but I'm going to do more investigating to see whether it can drop-in replace a 9900, which might be interesting. Anyone know whether this can be done and/or tried it? Also, has anyone here used both the TM990 and AMPL development systems enough to tell me if they aren't essentially the same software-wise? Thx in advance. jbdigriz