cdr
/ku'dr/ or /kuh'dr/ [from LISP] vt. To skip past the first item from a list of things (generalized from the LISP operation on binary tree structures, which returns a list consisting of all but the first element of its argument). In the form `cdr down', to trace down a list of elements: "Shall we cdr down the agenda?" Usage: silly. See also {loop through}.
Historical note: The instruction format of the IBM 7090 that hosted the original LISP implementation featured two 15-bit fields called the `address' and `decrement' parts. The term `cdr' was originally `Contents of Decrement part of Register'. Similarly, `car' stood for `Contents of Address part of Register'.
The cdr and car operations have since become bases for formation of compound metaphors in non-LISP contexts. GLS recalls, for example, a programming project in which strings were represented as linked lists; the get-character and skip-character operations were of course called CHAR and CHDR.
chad
/chad/ n. 1. The perforated edge strips on printer paper, after they have been separated from the printed portion. Also called {selvage} and {perf}. 2. obs. The confetti-like paper bits punched out of cards or paper tape; this was also called `chaff', `computer confetti', and `keypunch droppings'.
Historical note: One correspondent believes `chad' (sense 2) derives from the Chadless keypunch (named for its inventor), which cut little u-shaped tabs in the card to make a hole when the tab folded back, rather than punching out a circle/rectangle; it was clear that if the Chadless keypunch didn't make them, then the stuff that other keypunches made had to be `chad'.
chad box
n. {Iron Age} card punches contained boxes inside them, about the size of a lunchbox (or in some models a large wastebasket), that held the {chad} (sense 2). You had to open the covers of the card punch periodically and empty the chad box. The {bit bucket} was notionally the equivalent device in the CPU enclosure, which was typically across the room in another great gray-and-blue box.