8086 memory space was: The Soul of Barb's New Machine 1165

back in the 1970's, i helped out a guy who had two floppy disk TRS80's in his office. they came with this single-program, single-file 'inventory' system. his people made only a couple of updates a day (it was Dr. Pepper promo stuff - big painted wall-clocks for bars and so forth) and he kept 'phoning me up saying this count was wrong or that count was wrong so they were having to reconcile every day and i'd go over to his place after work and go through all this monolithic Basic code. just couldn't see what was wrong. but they were also updating in duplicate (both machines) so it was clear that something was screwy. this went on for weeks until one evening i heard the big photocopier in the next room fire up. at that very moment i was looking at the screen and saw a couple of numbers change seemingly all by themselves (this was not a networked system). i noticed that the copier was on the same circuit as the TRS80's, then got them to make some more copies and sure enough, some more numbers changed. we put the trs80's on their own different ciruit and they never had that problem again, at least as far as anybody could tell.

a hardware guy told me that the TRS80's didn't have parity-checking, but i forget whether he was talking about the memory or the cpu or whatever.

i remember some flipped bits on a Telex 9-track tape drive too, but couldn't duplicate the problem on demand and the service people told my boss i didn't know what i was talking about.

pc

TCS