:tired iron: /n./ [IBM] Hardware that is perfectly functional but far
enough behind the state of the art to have been superseded by new
products, presumably with sufficient improvement in bang-per-buck
that the old stuff is starting to look a bit like a {dinosaur}.
:tits on a keyboard: /n./ Small bumps on certain keycaps to keep touch-typists registered (usually on the `5' of a numeric keypad, and on the `F' and `J' of a {QWERTY} keyboard; but the Mac, perverse as usual, has them on the `D' and `K' keys).
:TLA: /T-L-A/ /n./ [Three-Letter Acronym] 1. Self-describing abbreviation for a species with which computing terminology is infested. 2. Any confusing acronym. Examples include MCA, FTP, SNA, CPU, MMU, SCCS, DMU, FPU, NNTP, TLA. People who like this looser usage argue that not all TLAs have three letters, just as not all four-letter words have four letters. One also hears of `ETLA' (Extended Three-Letter Acronym, pronounced /ee tee el ay/) being used to describe four-letter acronyms. The term `SFLA' (Stupid Four-Letter Acronym) has also been reported. See also {YABA}.
The self-effacing phrase "TDM TLA" (Too Damn Many…) is often used to bemoan the plethora of TLAs in use. In 1989, a random of the journalistic persuasion asked hacker Paul Boutin "What do you think will be the biggest problem in computing in the 90s?" Paul's straight-faced response: "There are only 17,000 three-letter acronyms." (To be exact, there are 26^3 = 17,576.)
:TMRC: /tmerk'/ /n./ The Tech Model Railroad Club at MIT, one of the wellsprings of hacker culture. The 1959 "Dictionary of the TMRC Language" compiled by Peter Samson included several terms that became basics of the hackish vocabulary (see esp. {foo}, {mung}, and {frob}).
By 1962, TMRC's legendary layout was already a marvel of complexity (and has grown in the thirty years since; all the features described here are still present). The control system alone featured about 1200 relays. There were {scram switch}es located at numerous places around the room that could be thwacked if something undesirable was about to occur, such as a train going full-bore at an obstruction. Another feature of the system was a digital clock on the dispatch board, which was itself something of a wonder in those bygone days before cheap LEDs and seven-segment displays. When someone hit a scram switch the clock stopped and the display was replaced with the word `FOO'; at TMRC the scram switches are therefore called `foo switches'.
Steven Levy, in his book "Hackers" (see the {Bibliography} in Appendix C), gives a stimulating account of those early years. TMRC's Power and Signals group included most of the early PDP-1 hackers and the people who later became the core of the MIT AI Lab staff. Thirty years later that connection is still very much alive, and this lexicon accordingly includes a number of entries from a recent revision of the TMRC dictionary.
:TMRCie: /tmerk'ee/, /n./ [MIT] A denizen of {TMRC}.
:to a first approximation: /adj./ 1. [techspeak] When one is doing certain numerical computations, an approximate solution may be computed by any of several heuristic methods, then refined to a final value. By using the starting point of a first approximation of the answer, one can write an algorithm that converges more quickly to the correct result. 2. In jargon, a preface to any comment that indicates that the comment is only approximately true. The remark "To a first approximation, I feel good" might indicate that deeper questioning would reveal that not all is perfect (e.g., a nagging cough still remains after an illness).
:to a zeroth approximation: [from `to a first approximation'] A *really* sloppy approximation; a wild guess. Compare {social science number}.