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, in software, 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 returned to use in the early 1990s on some RISC architectures because it consumes such an infinitesimal part of the processor that it actually makes sense not to have a UART. Compare {cycle of reincarnation}.
: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}, and other smaller-than-character-sized pieces of data; these include low-level device control, encryption algorithms, checksum and error-correcting codes, hash functions, some flavors of graphics programming (see {bitblt}), and assembler/compiler code generation. May connote either tedium or a real technical challenge (more usually the former). "The command decoding for the new tape driver looks pretty solid but the bit-bashing for the control registers still has bugs." See also {bit bang}, {mode bit}.
:bit bucket: /n./ 1. The universal data sink (originally, the mythical receptacle used to catch bits when they fall off the end of a register during a shift instruction). Discarded, lost, or destroyed data is said to have `gone to the bit bucket'. On {{Unix}}, often used for {/dev/null}. Sometimes amplified as `the Great Bit Bucket in the Sky'. 2. The place where all lost mail and news messages eventually go. The selection is performed according to {Finagle's Law}; important mail is much more likely to end up in the bit bucket than junk mail, which has an almost 100% probability of getting delivered. Routing to the bit bucket is automatically performed by mail-transfer agents, news systems, and the lower layers of the network. 3. The ideal location for all unwanted mail responses: "Flames about this article to the bit bucket." Such a request is guaranteed to overflow one's mailbox with flames. 4. Excuse for all mail that has not been sent. "I mailed you those figures last week; they must have landed in the bit bucket." Compare {black hole}.
This term is used purely in jest. It is based on the fanciful notion that bits are objects that are not destroyed but only misplaced. This appears to have been a mutation of an earlier term `bit box', about which the same legend was current; old-time hackers also report that trainees used to be told that when the CPU stored bits into memory it was actually pulling them `out of the bit box'. See also {chad box}.
Another variant of this legend has it that, as a consequence of the `parity preservation law', the number of 1 bits that go to the bit bucket must equal the number of 0 bits. Any imbalance results in bits filling up the bit bucket. A qualified computer technician can empty a full bit bucket as part of scheduled maintenance.
:bit decay: /n./ See {bit rot}. People with a physics background tend to prefer this variant for the analogy with particle decay. See also {computron}, {quantum bogodynamics}.
:bit rot: /n./ Also {bit decay}. Hypothetical disease the existence of which has been deduced from the observation that unused programs or features will often stop working after sufficient time has passed, even if `nothing has changed'. The theory explains that bits decay as if they were radioactive. As time passes, the contents of a file or the code in a program will become increasingly garbled.
There actually are physical processes that produce such effects (alpha particles generated by trace radionuclides in ceramic chip packages, for example, can change the contents of a computer memory unpredictably, and various kinds of subtle media failures can corrupt files in mass storage), but they are quite rare (and computers are built with error-detecting circuitry to compensate for them). The notion long favored among hackers that cosmic rays are among the causes of such events turns out to be a myth; see the {cosmic rays} entry for details.