A bit is said to be `set' if its value is true or 1, and
`reset' or `clear' if its value is false or 0. One speaks of
setting and clearing bits. To {toggle} or `invert' a bit is
to change it, either from 0 to 1 or from 1 to 0. See also
{flag}, {trit}, {mode bit}.

The term `bit' first appeared in print in the computer-science
sense in 1949, and seems to have been coined by early computer
scientist John Tukey. Tukey records that it evolved over a lunch
table as a handier alternative to `bigit' or `binit'.

:bit bang: n. Transmission of data on a serial line, when
accomplished by rapidly tweaking a single output bit at the
appropriate times. The technique is a simple
loop with eight OUT and SHIFT instruction pairs for each byte.
Input is more interesting. And full duplex (doing input and output
at the same time) is one way to separate the real hackers from the
{wannabee}s.

Bit bang was used on certain early models of Prime computers,
presumably when UARTs were too expensive, and on archaic Z80 micros
with a Zilog PIO but no SIO. In an interesting instance of the
{cycle of reincarnation}, this technique is now (1991) coming
back into use on some RISC architectures because it consumes such
an infinitesimal part of the processor that it actually makes sense
not to have a UART.

:bit bashing: n. (alt. `bit diddling' or {bit twiddling}) Term
used to describe any of several kinds of low-level programming
characterized by manipulation of {bit}, {flag}, {nybble},