"to put into code," 1815, from code (n.). Specifically "to put into computer code" from 1947. Intransitive sense "write computer code" is by 1987. Related: Coded; coding.
early 15c., "readiness" (in phrase in prompte), from Latin promptus (see prompt (v.)). Meaning "hint, information suggested, act of prompting" is from 1590s. The computer sense of "message given by a computer requiring or helping the user to respond" is by 1977.