CDR

Accessor of the second element of a Lisp cons cell. Unlike the accessor of the first element, car, it does not suffer a namespace collision with a common English word.

The CDR(Current Dependent Resistor) is a refinement of the PTC thermistor. It's a relatively new component. The CDR has a more instant switch from low(a few ohms) to a high resistance(several kiloohms) than the PTC.

The CDR is manufactured for different 'switching' currents, and is used instead of a fuse. If the current through the CDR gets higher than the switching current the temperature in the component rises. This causes the resistance to rise rapidly, thous protecting the rest of the electronics in the circuit. When the temperature falls again, the resistance returns to the low state.

CDA = C = chad

cdr /ku'dr/ or /kuh'dr/ vt.

[from LISP] 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 704 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.

--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.