The top bit of an 8-bit character, which is on in character values
128--255. Also called high bit,
alt bit. Some terminals and consoles (see
space-cadet keyboard) have a META shift key. Others (including,
mirabile dictu, keyboards on IBM PC-class machines)
have an ALT key. See also bucky bits.
Historical note: although in modern usage shaped by a universe of
8-bit bytes the meta bit is invariably hex 80 (octal 0200), things were
different on earlier machines with 36-bit words and 9-bit bytes. The MIT
and Stanford keyboards (see space-cadet keyboard)
generated hex 100 (octal 400) from their meta keys.
