A condition endemic to some now-obsolete computers and peripherals (including ASR-33 teletypes and PRIME minicomputers) that results in all characters having their high (0x80) bit forced on. This of course makes transporting files to other systems much more difficult, not to mention the problems these machines have talking with true 8-bit devices.
This term was originally used specifically of PRIME (a.k.a. PR1ME) minicomputers. Folklore has it that PRIME adopted the reversed-8-bit convention in order to save 25 cents per serial line per machine; PRIME old-timers, on the other hand, claim they inherited the disease from Honeywell via customer NASA's compatibility requirements and struggled heroically to cure it. Whoever was responsible, this probably qualifies as one of the most cretinous design tradeoffs ever made. See meta bit.