Aduke.1785 net.general utcsrgv!utzoo!decvax!duke!dbl Wed Feb 17 11:39:40 1982 Re: utcsrgv.125 :Info on PDP12 The PDP-12! Ahh, what fond memories I have... As far as maintainability is concerned, most of what makes up the PDP-12 consists of logic modules out of DEC's old Flip Chip(TM) logic series. Though this also means it has a tendency to give off a lot of heat. Problems can be traced to the board and chip level, if you're up to it, have a complete set of prints, and the diagnostics. The 12, in case you don't know, is a dual processor machine. The two processors, a more modern version of the old LINC lab computer and an early version of the PDP-8, share common memory, but do not operate concurrently. The LINC processor has the instructions for accessing the D/A, A/D, relays, display scope, and the LINCtapes (a little different than DECtapes, but not much). The PDP-8 portion has most of the familiar PDP-8 instructions set, so most PDP-8 software will run in 8-mode, and all terminal traffic is handled through the PDP-8 I/O bus. Programming can be a little hairy, for various reasons. You DO have to do everything yourself, I/O routines, interrupt service, etc. but what do you expect? Also the interrupt vector address and memory addressing is handled differently by the two processors even though it is the same memory. It has a reasonable editor which uses the display screen. Assembly can take what seems like forever on the LINCtapes, but the assembler is pretty nice, having things that you wouldn't expect to find such as a conditional assembly facility. ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.