alex@grian.cps.altadena.ca.us (Alex Pournelle) (03/14/91)
I ran into a really really wierd one today--thought I'd share it with you. System that previously worked fine, suddenly stopped --when booted up, it wouldn't get past cron startup. Just crashes. Looked at it for a while -- suddenly realized that the customer had taken the printer away, but left the parallel printer cable connected. Removed it, rebooted, and it's fine. What could have been a panicky multi-hour problem turned out to be ten minutes' luck. Damfino how a simple cable could cause cron to hang, though. ANY idea? Cable seems fine, on MS-DOS systems. You'll understand I'm not too interested in trying it on the XENIX system! Alex -- Alex Pournelle, freelance thinker Also: Workman & Associates, Data recovery for PCs, Macs, others ...elroy!grian!alex; BIX: alex; voice: (818) 791-7979 fax: (818) 794-2297 bbs: 791-1013; 8N1 24/12/3
rmk@rmkhome.UUCP (Rick Kelly) (03/20/91)
In article <1991Mar14.085304.4906@grian.cps.altadena.ca.us> alex@grian.cps.altadena.ca.us (Alex Pournelle) writes: >I ran into a really really wierd one today--thought I'd share it with >you. > >System that previously worked fine, suddenly stopped --when booted up, >it wouldn't get past cron startup. Just crashes. > >Looked at it for a while -- suddenly realized that the customer had >taken the printer away, but left the parallel printer cable connected. >Removed it, rebooted, and it's fine. What could have been a panicky >multi-hour problem turned out to be ten minutes' luck. Damfino how a >simple cable could cause cron to hang, though. > >ANY idea? Cable seems fine, on MS-DOS systems. You'll understand I'm >not too interested in trying it on the XENIX system! That unterminated parallel cable probably makes a fine antenna. The system is broadcasting it's own noise back to the cpu. Probably causes some wierd spurious interrupt that XENIX doesn't like. Serial cables can do the same thing. Rick Kelly rmk@rmkhome.UUCP frog!rmkhome!rmk rmk@frog.UUCP
wht@n4hgf.Mt-Park.GA.US (Warren Tucker) (03/23/91)
In article <537@bria> uunet!bria!mike writes: >In an article, rmk@rmkhome.UUCP (Rick Kelly) writes: >|That unterminated parallel cable probably makes a fine antenna. >Would putting some kind of wrap-plug on the cable ends help this? Best to unplug the parallel cable from the box. ---------------------------------------------------------------------------- Warren Tucker, TuckerWare, Mountain Park, GA wht@n4hgf.Mt-Park.GA.US "The computer can't tell you the emotional story. It can give you the exact mathematical design, but what's missing is the eyebrows." -- Frank Zappa
rmk@rmkhome.UUCP (Rick Kelly) (03/24/91)
In article <537@bria> uunet!bria!mike writes: >In an article, rmk@rmkhome.UUCP (Rick Kelly) writes: >|That unterminated parallel cable probably makes a fine antenna. The system is >|broadcasting it's own noise back to the cpu. Probably causes some wierd >|spurious interrupt that XENIX doesn't like. Serial cables can do the same >|thing. > >Would putting some kind of wrap-plug on the cable ends help this? >Just curious. Since PC's tend to reset the parallel port on cold boot, a loopback cable could also cause problems with booting. Parallel cables are least sensitive when the shield is grounded on both ends. This is why good cables have some metal that comes into contact with the printer's connector. Being only grounded on 1 end, makes the cables shield a very powerful antenna. Rick Kelly rmk@rmkhome.UUCP frog!rmkhome!rmk rmk@frog.UUCP