Gentle persons: I love these stories!
I'm sorry, Gene, that you had such a bad experience. I can only protest that a PDP11/23 wasn't a *real* PDP11. It came out nearly a decade after the 11/20, had an LSI-based CPU instead of a boatload of M-series logic, used the Q-bus instead of the Unibus, and (the most telling point for me) didn't have a *real* front panel. All this is just rationalization, of course. The truth is, you had to deal with a lemon at a time when DEC was already beginning to reel from competition and market conditions. I (technically my advisor, since it was his grant money, but it was my lab partner and I who made the case and wrote the requisition) took possession of the third PDP11 sold out of DEC's Chicago office. As affordable as it was, it was so expensive compared to our research budget that we had to buy the CPU, ASR33 teletype, and power supply out of one grant, the 4(yes, 4!)-Kiloword core memory module out of another, and the high-speed paper tape reader/punch and relay rack out of a third. The system pictured on the home page http://hampage.hu/pdp-11/ might as well have have been my system. The model line was so new that my escutcheon plate said "PDP11" and not "PDP11/20" as it did on later machines. It was so early in the production cycle that I got documentation in the form of a set of E-sized drawings red-lined with the ECOs installed during manufacturing and a bunch of prepublication drafts of manuals. Of course, all those last-minute ECOs meant my backplane was chock full of colorful wire-wrapped patches. With the exception of inevitable core-memory issues (what minicomputer maker didn't have to run core-memory tests all the time?), the only real problems I ever had over the years were inevitably the result of forgetting to observe proper Unibus etiquette or screwing up my wire wrapping. When I complained about the lack of software documentation, the DEC Field Service Engineer surreptitiously passed me a number of source-code distributions which I cheerfully pored through at night while my experiments were running. It didn't take me long to discover that some of the early software was actually PDP8 software mangled so a PDP11 could interpret it, albeit slowly (not nothing did the PDP11 instruction set include the EMT, or emulate trap, instruction). I was the best of friends with the Chicago office after I showed them my version of BASIC-11 running 4 times faster than theirs because I had replaced the emulated instructions with native code. I didn't do it for them. Real men wrote only in assembler or directly in machine code. I had to make BASIC work well because my advisor was hopeless with anything else and he had some experiments of his own to run. In defense of my taking up bandwidth on the EMC mailing list, the reason we bought this PDP11 was to control and monitor a very large and complicated experimental apparatus. Like a fly-by-wire aircraft, this system would have crashed and burned if it weren't for computer-based real*-time command, control, data acquisition, and processing. *I say "real" time, but keep in mind this was the early 1970s. I wrote my software and meticulously counted cycles before RSX11M or its country-cousin RT11 were available. Later, I got to spend some time debugging an RSX11M program as a favor to a medical researcher at the same university. Yikes. Regards, Kent ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
