Newsgroups: alt.folklore.computers,alt.sys.pdp10 Subject: Computer lights in dark rooms (was Re: WHAT IS A MAINFRAME???) References: <39555E4A.463A37CE@altnews.com.au> <39564AF8.8A6F136C@earthlink.net> From: Ric Werme X-Newsreader: NN version 6.5.0 CURRENT #119 Lines: 39 Message-ID: Date: Mon, 26 Jun 2000 01:00:40 GMT NNTP-Posting-Host: 24.91.12.15 X-Complaints-To: abuse@mediaone.net X-Trace: typhoon.ne.mediaone.net 961981240 24.91.12.15 (Sun, 25 Jun 2000 21:00:40 EDT) NNTP-Posting-Date: Sun, 25 Jun 2000 21:00:40 EDT Organization: Road Runner Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!isdnet!newsfeed.cwix.com!chnws02.mediaone.net!chnws05.ne.mediaone.net!24.128.8.70!typhoon.ne.mediaone.net.POSTED!not-for-mail Xref: chonsp.franklin.ch alt.folklore.computers:58599 jchausler writes: >> Conversely, I think there's few things prettier than a computer room >> after lights-out. >> A veritable fairyland of glimmering LEDs and softly glowing terminals. >When working graveyard shift at this same school, when we'd run out >the job queue, we would frequently turn off the machine room lights. >As one who is very nearsighted, I would then take my glasses off. The >lamps would become flickering orbs, quite pretty, and since this was the >late 60's quite psychedelic as well :-) The 360/67 was good but the >UNIVAC 1108 was the best. I had the assignment once to write a memory diagnostic for a PDP-10 "at this same school" (hey, Chris, why the sealed lips?). The system had occasional errors that DEC diagnostics couldn't catch. This was before they had diagnostics that would exercise multiple memory ports simutaneouly. So I wrote something that would run a set of patterns against the Bryant drum (RM10B), our fastest peripheral, and gave that the highest interrupt level. Next came the disk drives (RP03s or equivalents). In the system's spare time the CPU did similar stuff. It kept most of the boxes very busy. The console lights jumped around the most, the several memory boxes were a little less, and the data channels showed the patterns in sequence, but at different rates. With lights out it was stunning. I had never seen that system or any other look as busy. Around the time I got it going, the engineering lab discovered that some core planes were shorting out due to vibration wearing down the magnet wire insulation. But the program did cause and detect some parity errors that DEC's diagnostics didn't. One of our memory boxes was a RCA prototype that had red, green, and white incandescents. (Filters....) It was always Christmasy. -Ric Werme -- Ric Werme | werme@nospam.mediaone.net http://people.ne.mediaone.net/werme | ^^^^^^^ delete