Words starting with bitpl
Maybe these words will be useful:
- bit bang — Transmission of data on a serial line accomplished by rapidly changing 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 wannabees. Bit bang was used on certain early models of Prime computers, presumably when UARTs were too expensive, and on archaic Zilog 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 — (Also "bit diddling" or bit twiddling). Any of several kinds of low-level programming characterised by manipulation of bit, flag, nibble, 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 flavours 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 — (jargon) 1. (Or "write-only memory", "WOM") 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". 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. In contrast, a "chad box" is a real container used to catch chad. This may be related to the origin of the term "bit bucket" [Comments ?].
- bit decay — bit rot
- bit diddling — bit bashing
- bit field — (data) Part of an item of data, storage location or message, identified as a certain number of contiguous bits starting at a certain bit position within the data. Bit position zero is usually the least significant bit. For example, in an ARM machine code instruction the four-bit field at bits 28 to 31 (the four most significant bits in the 32-bit word) is the "condition code".
- bit mask — (programming) A pattern of binary values which is combined with some value using bitwise AND with the result that bits in the value in positions where the mask is zero are also set to zero. For example, if, in C, we want to test if bits 0 or 2 of x are set, we can write int mask = 5; /* binary 101 */ if (x & mask) ... A bit mask might also be used to set certain bits using bitwise OR, or to invert them using bitwise exclusive OR.
- bit pattern — (data) A sequence of bits, in a memory, a communications channel or some other device. The term is used to contrast this with some higher level interpretation of the bits such as an integer or an image. A bit string is similar but suggests an arbitrary, as opposed to predetermined, length.
- bit plane — (graphics) (Or "bitplane") The memory in a graphic display device which holds a complete one-bit-per-pixel image. Several bit planes may be used in conjunction to give more bits per pixel or to overlay several images or mask one with another. "Bit plane" may be used as a synonym for "bitmap", though the latter suggests the data itself rather than the memory and also suggests a graphics file format.
- bit rot — (jargon) A 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. People with a physics background tend to prefer the variant "bit decay" for the analogy with particle decay. 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 detection circuitry to compensate for them). The notion long favoured among hackers that cosmic rays are among the causes of such events turns out to be a myth. Bit rot is the notional cause of software rot. See also computron, quantum bogodynamics.