"a stew of meat cut into small pieces," 1660s, from hash (v.). Meaning "a mix, a mess" is from 1735. Cryptographic use in computing is by 1979.
1960, in computing, "sequence of one or more characters used to specify the beginning or end of separate, independent regions in text or other data streams," agent noun from delimit.
1630s, "determine by calculation," from French computer (16c.), from Latin computare "to count, sum up, reckon together," from com "with, together" (see com-) + putare "to reckon," originally "to prune," from PIE root *pau- (2) "to cut, strike, stamp." A doublet of count (v.). Related: Computed; computing.