Part 6

:bit: [from the mainstream meaning and `Binary digIT'] n. 1. [techspeak] The unit of information; the amount of information obtained by asking a yes-or-no question for which the two outcomes are equally probable. 2. [techspeak] A computational quantity that can take on one of two values, such as true and false or 0 and 1. 3. A mental flag: a reminder that something should be done eventually. "I have a bit set for you." (I haven't seen you for a while, and I'm supposed to tell or ask you something.) 4. More generally, a (possibly incorrect) mental state of belief. "I have a bit set that says that you were the last guy to hack on EMACS." (Meaning "I think you were the last guy to hack on EMACS, and what I am about to say is predicated on this, so please stop me if this isn't true.")

"I just need one bit from you" is a polite way of indicating that you intend only a short interruption for a question that can presumably be answered yes or no.

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}, 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 ended 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 one 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.

The term {software rot} is almost synonymous. Software rot is the effect, bit rot the notional cause.

:bit twiddling: n. 1. (pejorative) An exercise in tuning (see {tune}) in which incredible amounts of time and effort go to produce little noticeable improvement, often with the result that the code has become incomprehensible. 2. Aimless small modification to a program, esp. for some pointless goal. 3. Approx. syn. for {bit bashing}; esp. used for the act of frobbing the device control register of a peripheral in an attempt to get it back to a known state.

:bit-paired keyboard: n. obs. (alt. `bit-shift keyboard') A non-standard keyboard layout that seems to have originated with the Teletype ASR-33 and remained common for several years on early computer equipment. The ASR-33 was a mechanical device (see {EOU}), so the only way to generate the character codes from keystrokes was by some physical linkage. The design of the ASR-33 assigned each character key a basic pattern that could be modified by flipping bits if the SHIFT or the CTRL key was pressed. In order to avoid making the thing more of a Rube Goldberg kluge than it already was, the design had to group characters that shared the same basic bit pattern on one key.

Looking at the ASCII chart, we find:

high low bits bits 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 010 ! " # $ % & ' ( ) 011 0 1 2 3 4 5 6 7 8 9

This is why the characters !"#$%&'() appear where they do on a Teletype (thankfully, they didn't use shift-0 for space). This was *not* the weirdest variant of the {QWERTY} layout widely seen, by the way; that prize should probably go to one of several (differing) arrangements on IBM's even clunkier 026 and 029 card punches.

When electronic terminals became popular, in the early 1970s, there was no agreement in the industry over how the keyboards should be laid out. Some vendors opted to emulate the Teletype keyboard, while others used the flexibility of electronic circuitry to make their product look like an office typewriter. These alternatives became known as `bit-paired' and `typewriter-paired' keyboards. To a hacker, the bit-paired keyboard seemed far more logical --- and because most hackers in those days had never learned to touch-type, there was little pressure from the pioneering users to adapt keyboards to the typewriter standard.

The doom of the bit-paired keyboard was the large-scale introduction of the computer terminal into the normal office environment, where out-and-out technophobes were expected to use the equipment. The `typewriter-paired' standard became universal, `bit-paired' hardware was quickly junked or relegated to dusty corners, and both terms passed into disuse.

:bitblt: /bit'blit/ n. [from {BLT}, q.v.] 1. Any of a family of closely related algorithms for moving and copying rectangles of bits between main and display memory on a bit-mapped device, or between two areas of either main or display memory (the requirement to do the {Right Thing} in the case of overlapping source and destination rectangles is what makes BitBlt tricky). 2. Synonym for {blit} or {BLT}. Both uses are borderline techspeak.

:BITNET: /bit'net/ [acronym: Because It's Time NETwork] n. Everybody's least favorite piece of the network (see {network, the}). The BITNET hosts are a collection of IBM dinosaurs and VAXen (the latter with lobotomized comm hardware) that communicate using 80-character {{EBCDIC}} card images (see {eighty-column mind}); thus, they tend to mangle the headers and text of third-party traffic from the rest of the ASCII/RFC-822 world with annoying regularity. BITNET is also notorious as the apparent home of {BIFF}.

:bits: n.pl. 1. Information. Examples: "I need some bits about file formats." ("I need to know about file formats.") Compare {core dump}, sense 4. 2. Machine-readable representation of a document, specifically as contrasted with paper: "I have only a photocopy of the Jargon File; does anyone know where I can get the bits?". See {softcopy}, {source of all good bits} See also {bit}.

:bitty box: /bit'ee boks/ n. 1. A computer sufficiently small, primitive, or incapable as to cause a hacker acute claustrophobia at the thought of developing software on or for it. Especially used of small, obsolescent, single-tasking-only personal machines such as the Atari 800, Osborne, Sinclair, VIC-20, TRS-80, or IBM PC. 2. [Pejorative] More generally, the opposite of `real computer' (see {Get a real computer!}). See also {mess-dos}, {toaster}, and {toy}.

:bixie: /bik'see/ n. Variant {emoticon}s used on BIX (the Byte Information eXchange). The {smiley} bixie is <@_@>, apparently intending to represent two cartoon eyes and a mouth. A few others have been reported.

:black art: n. A collection of arcane, unpublished, and (by implication) mostly ad-hoc techniques developed for a particular application or systems area (compare {black magic}). VLSI design and compiler code optimization were (in their beginnings) considered classic examples of black art; as theory developed they became {deep magic}, and once standard textbooks had been written, became merely {heavy wizardry}. The huge proliferation of formal and informal channels for spreading around new computer-related technologies during the last twenty years has made both the term `black art' and what it describes less common than formerly. See also {voodoo programming}.

:black hole: n. When a piece of email or netnews disappears mysteriously between its origin and destination sites (that is, without returning a {bounce message}) it is commonly said to have `fallen into a black hole'. "I think there's a black hole at foovax!" conveys suspicion that site foovax has been dropping a lot of stuff on the floor lately (see {drop on the floor}). The implied metaphor of email as interstellar travel is interesting in itself. Compare {bit bucket}.

:black magic: n. A technique that works, though nobody really understands why. More obscure than {voodoo programming}, which may be done by cookbook. Compare also {black art}, {deep magic}, and {magic number} (sense 2).

:blargh: /blarg/ [MIT] n. The opposite of {ping}, sense 5; an exclamation indicating that one has absorbed or is emitting a quantum of unhappiness. Less common than {ping}.

:blast: 1. vt.,n. Synonym for {BLT}, used esp. for large data sends over a network or comm line. Opposite of {snarf}. Usage: uncommon. The variant `blat' has been reported. 2. vt. [HP/Apollo] Synonymous with {nuke} (sense 3). Sometimes the message `Unable to kill all processes. Blast them (y/n)?' would appear in the command window upon logout.

:blat: n. 1. Syn. {blast}, sense 1. 2. See {thud}.

:bletch: /blech/ [from Yiddish/German `brechen', to vomit, poss. via comic-strip exclamation `blech'] interj. Term of disgust. Often used in "Ugh, bletch". Compare {barf}.

:bletcherous: /blech'*-r*s/ adj. Disgusting in design or function; esthetically unappealing. This word is seldom used of people. "This keyboard is bletcherous!" (Perhaps the keys don't work very well, or are misplaced.) See {losing}, {cretinous}, {bagbiter}, {bogus}, and {random}. The term {bletcherous} applies to the esthetics of the thing so described; similarly for {cretinous}. By contrast, something that is `losing' or `bagbiting' may be failing to meet objective criteria. See also {bogus} and {random}, which have richer and wider shades of meaning than any of the above.

:blinkenlights: /blink'*n-li:tz/ n. Front-panel diagnostic lights on a computer, esp. a {dinosaur}. Derives from the last word of the famous blackletter-Gothic sign in mangled pseudo-German that once graced about half the computer rooms in the English-speaking world. One version ran in its entirety as follows:

ACHTUNG! ALLES LOOKENSPEEPERS! Das computermachine ist nicht fuer gefingerpoken und mittengrabben. Ist easy schnappen der springenwerk, blowenfusen und poppencorken mit spitzensparken. Ist nicht fuer gewerken bei das dumpkopfen. Das rubbernecken sichtseeren keepen das cotten-pickenen hans in das pockets muss; relaxen und watchen das blinkenlichten.

This silliness dates back at least as far as 1959 at Stanford University and had already gone international by the early 1960s, when it was reported at London University's ATLAS computing site. There are several variants of it in circulation, some of which actually do end with the word `blinkenlights'.

In an amusing example of turnabout-is-fair-play, German hackers have developed their own versions of the blinkenlights poster in fractured English, one of which is reproduced here:

ATTENTION This room is fullfilled mit special electronische equippment. Fingergrabbing and pressing the cnoeppkes from the computers is allowed for die experts only! So all the "lefthanders" stay away and do not disturben the brainstorming von here working intelligencies. Otherwise you will be out thrown and kicked anderswhere! Also: please keep still and only watchen astaunished the blinkenlights.

See also {geef}.

:blit: /blit/ vt. 1. To copy a large array of bits from one part of a computer's memory to another part, particularly when the memory is being used to determine what is shown on a display screen. "The storage allocator picks through the table and copies the good parts up into high memory, and then blits it all back down again." See {bitblt}, {BLT}, {dd}, {cat}, {blast}, {snarf}. More generally, to perform some operation (such as toggling) on a large array of bits while moving them. 2. All-capitalized as `BLIT': an early experimental bit-mapped terminal designed by Rob Pike at Bell Labs, later commercialized as the AT&T 5620. (The folk etymology from `Bell Labs Intelligent Terminal' is incorrect.)

:blitter: /blit'r/ n. A special-purpose chip or hardware system built to perform {blit} operations, esp. used for fast implementation of bit-mapped graphics. The Commodore Amiga and a few other micros have these, but in 1991 the trend is away from them (however, see {cycle of reincarnation}). Syn. {raster blaster}.

:blivet: /bliv'*t/ [allegedly from a World War II military term meaning "ten pounds of manure in a five-pound bag"] n. 1. An intractable problem. 2. A crucial piece of hardware that can't be fixed or replaced if it breaks. 3. A tool that has been hacked over by so many incompetent programmers that it has become an unmaintainable tissue of hacks. 4. An out-of-control but unkillable development effort. 5. An embarrassing bug that pops up during a customer demo.

This term has other meanings in other technical cultures; among experimental physicists and hardware engineers of various kinds it seems to mean any random object of unknown purpose (similar to hackish use of {frob}). It has also been used to describe an amusing trick-the-eye drawing resembling a three-pronged fork that appears to depict a three-dimensional object until one realizes that the parts fit together in an impossible way.

:BLOB: [acronym, Binary Large OBject] n. Used by database people to refer to any random large block of bits which needs to be stored in a database, such as a picture or sound file. The essential point about a BLOB is that it's an object you can't interpret within the database itself.

:block: [from process scheduling terminology in OS theory] 1. vi. To delay or sit idle while waiting for something. "We're blocking until everyone gets here." Compare {busy-wait}. 2. `block on' vt. To block, waiting for (something). "Lunch is blocked on Phil's arrival."

:block transfer computations: n. From the television series "Dr. Who", in which it referred to computations so fiendishly subtle and complex that they could not be performed by machines. Used to refer to any task that should be expressible as an algorithm in theory, but isn't.

:blow an EPROM: /bloh *n ee'prom/ v. (alt. `blast an EPROM', `burn an EPROM') To program a read-only memory, e.g. for use with an embedded system. This term arises because the programming process for the Programmable Read-Only Memories (PROMs) that preceded present-day Erasable Programmable Read-Only Memories (EPROMs) involved intentionally blowing tiny electrical fuses on the chip. Thus, one was said to `blow' (or `blast') a PROM, and the terminology carried over even though the write process on EPROMs is nondestructive.

:blow away: vt. To remove (files and directories) from permanent storage, generally by accident. "He reformatted the wrong partition and blew away last night's netnews." Oppose {nuke}.

:blow out: vi. Of software, to fail spectacularly; almost as serious as {crash and burn}. See {blow past}, {blow up}, {die horribly}.

:blow past: vt. To {blow out} despite a safeguard. "The server blew past the 5K reserve buffer."

:blow up: vi. 1. [scientific computation] To become unstable. Suggests that the computation is diverging so rapidly that it will soon overflow or at least go {nonlinear}. 2. Syn. {blow out}.

:BLT: /B-L-T/, /bl*t/ or (rarely) /belt/ n.,vt. Synonym for {blit}. This is the original form of {blit} and the ancestor of {bitblt}. It referred to any large bit-field copy or move operation (one resource-intensive memory-shuffling operation done on pre-paged versions of ITS, WAITS, and TOPS-10 was sardonically referred to as `The Big BLT'). The jargon usage has outlasted the {PDP-10} BLock Transfer instruction from which {BLT} derives; nowadays, the assembler mnemonic {BLT} almost always means `Branch if Less Than zero'.

:Blue Book: n. 1. Informal name for one of the three standard references on the page-layout and graphics-control language {PostScript} (`PostScript Language Tutorial and Cookbook', Adobe Systems, Addison-Wesley 1985, QA76.73.P67P68, ISBN 0-201-10179-3); the other two official guides are known as the {Green Book}, the {Red Book}, and the {White Book} (sense 2). 2. Informal name for one of the three standard references on Smalltalk: `Smalltalk-80: The Language and its Implementation', David Robson, Addison-Wesley 1983, QA76.8.S635G64, ISBN 0-201-11371-63 (this is also associated with green and red books). 3. Any of the 1988 standards issued by the CCITT's ninth plenary assembly. Until now, they have changed color each review cycle (1984 was {Red Book}, 1992 would be {Green Book}); however, it is rumored that this convention is going to be dropped before 1992. These include, among other things, the X.400 email spec and the Group 1 through 4 fax standards. See also {{book titles}}.

:Blue Glue: [IBM] n. IBM's SNA (Systems Network Architecture), an incredibly {losing} and {bletcherous} communications protocol widely favored at commercial shops that don't know any better. The official IBM definition is "that which binds blue boxes together." See {fear and loathing}. It may not be irrelevant that {Blue Glue} is the trade name of a 3M product that is commonly used to hold down the carpet squares to the removable panel floors common in {dinosaur pen}s. A correspondent at U. Minn. reports that the CS department there has about 80 bottles of the stuff hanging about, so they often refer to any messy work to be done as `using the blue glue'.

:blue goo: n. Term for `police' {nanobot}s intended to prevent {gray goo}, denature hazardous waste, destroy pollution, put ozone back into the stratosphere, prevent halitosis, and promote truth, justice, and the American way, etc. See {{nanotechnology}}.

:blue wire: [IBM] n. Patch wires added to circuit boards at the factory to correct design or fabrication problems. This may be necessary if there hasn't been time to design and qualify another board version. Compare {purple wire}, {red wire}, {yellow wire}.

:blurgle: /bler'gl/ [Great Britain] n. Spoken {metasyntactic variable}, to indicate some text which is obvious from context, or which is already known. If several words are to be replaced, blurgle may well be doubled or trebled. "To look for something in several files use `grep string blurgle blurgle'." In each case, "blurgle blurgle" would be understood to be replaced by the file you wished to search. Compare {mumble}, sense 6.

:BNF: /B-N-F/ n. 1. [techspeak] Acronym for `Backus-Naur Form', a metasyntactic notation used to specify the syntax of programming languages, command sets, and the like. Widely used for language descriptions but seldom documented anywhere, so that it must usually be learned by osmosis from other hackers. Consider this BNF for a U.S. postal address:

<postal-address> ::= <name-part> <street-address> <zip-part>

<personal-part> ::= <name> | <initial> "."

<name-part> ::= <personal-part> <last-name> [<jr-part>] <EOL> | <personal-part> <name-part>

<street-address> ::= [<apt>] <house-num> <street-name> <EOL>

<zip-part> ::= <town-name> "," <state-code> <ZIP-code> <EOL>

This translates into English as: "A postal-address consists of a name-part, followed by a street-address part, followed by a zip-code part. A personal-part consists of either a first name or an initial followed by a dot. A name-part consists of either: a personal-part followed by a last name followed by an optional `jr-part' (Jr., Sr., or dynastic number) and end-of-line, or a personal part followed by a name part (this rule illustrates the use of recursion in BNFs, covering the case of people who use multiple first and middle names and/or initials). A street address consists of an optional apartment specifier, followed by a street number, followed by a street name. A zip-part consists of a town-name, followed by a comma, followed by a state code, followed by a ZIP-code followed by an end-of-line." Note that many things (such as the format of a personal-part, apartment specifier, or ZIP-code) are left unspecified. These are presumed to be obvious from context or detailed somewhere nearby. See also {parse}. 2. The term is also used loosely for any number of variants and extensions, possibly containing some or all of the {regexp} wildcards such as `*' or `+'. In fact the example above isn't the pure form invented for the Algol-60 report; it uses `[]', which was introduced a few years later in IBM's PL/I definition but is now universally recognized. 3. In {{science-fiction fandom}}, BNF means `Big-Name Fan' (someone famous or notorious). Years ago a fan started handing out black-on-green BNF buttons at SF conventions; this confused the hacker contingent terribly.

:boa: [IBM] n. Any one of the fat cables that lurk under the floor in a {dinosaur pen}. Possibly so called because they display a ferocious life of their own when you try to lay them straight and flat after they have been coiled for some time. It is rumored within IBM that channel cables for the 370 are limited to 200 feet because beyond that length the boas get dangerous --- and it is worth noting that one of the major cable makers uses the trademark `Anaconda'.

:board: n. 1. In-context synonym for {bboard}; sometimes used even for USENET newsgroups. 2. An electronic circuit board (compare {card}).