The Jargon File (version 4.4.7, 29 Dec 2003):

dread high-bit disease
 n.

    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.