v076n3w7@ubvms.cc.buffalo.edu (03/22/90)
I see that there is yet another person desperately searching for a Unix OS for the q-bus PDP systems. I am also looking for a copy of Unix for the PDP, but that is not why I am posting. On the note of 18- and 22-bit architectures, the 11/23 IS a 22-bit microcomputer. I know this as I am running an 11/23 with 1 meg of memory. The memory limitations, however, are in the backplane. If the backplane being used is a BA11-SA, then it's 22-bit. I forgot the other types of q-bus backplanes, but I think the BA11-N is 18- or 16-bit. Chris Kalisiak V076N3W7@ubvms.bitnet v076N3W7@cc.buffalo.edu
swilson@pprg.unm.edu (Scott Wilson [CHTM]) (03/22/90)
In article <694.26076f6d@ubvms.cc.buffalo.edu> v076n3w7@ubvms.cc.buffalo.edu writes: >The memory limitations, however, are in the backplane. > >If the backplane being used is a BA11-SA, then it's 22-bit. > >I forgot the other types of q-bus backplanes, but I think the >BA11-N is 18- or 16-bit. > >Chris Kalisiak >V076N3W7@ubvms.bitnet >v076N3W7@cc.buffalo.edu This is indeed the case. However, if you are brave, you can whip out your handy wire-wrap tool and add the missing lines to your backplane! I have done this several times. Just be sure to follow the LSI-11 Bus Technical Specs. This sometimes doesn't work (on real old backplanes) because DEC connected all the SPAREx lines that would later become BDAL{18-21} to the ground plane! On some other backplanes these were bussed between slots, but just werent used. On others they are not bussed, but not connected between slots either and these are the ones you can wire-wrap to be full Q22. Just be sure to keep the wires close the backplane or you may mess up the RF impedance of the added lines. Check out your backplane with VOM (and with all the cards out) before you start to be sure you get everything right. Scott Wilson University of New Mexico Center for High Technology Materials Albuqerque, NM 87131 (505)277-0780 swilson@bullwinkle.unm.edu