[vcf-midatlantic] DIP switches
Mike Loewen
mloewen at cpumagic.scol.pa.us
Wed Mar 27 23:12:16 EDT 2019
Don't neglect them while troubleshooting, especially the little red
bastards. :-) My HP 2647A graphics terminal developed what appeared to be a
sync problem when displaying more than one line of text. Swapping the suspect
cards with known good ones from another terminal didn't change a thing. All
self-tests passed, including text RAM and graphics RAM. Graphics mode worked
perfectly. I finally swapped the two RAM cards (32K on each), changing the
DIP switch configurations on each. At last, a RAM error. I excercised all of
the DIP switches, put everything back together and it worked.
This is the second time I've had problems with DIP switches in vintage HP
gear. The other was in a 2117F I was working on for Dave McGuire. Same cure.
Mike Loewen mloewen at cpumagic.scol.pa.us
Old Technology http://q7.neurotica.com/Oldtech/
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