accumulator

accumulator n.  1. Archaic term for a register.  On-line use
   of it as a synonym for `register' is a fairly reliable
   indication that the user has been around for quite a while and/or
   that the architecture under discussion is quite old.  The term in
   full is almost never used of microprocessor registers, for example,
   though symbolic names for arithmetic registers beginning in `A'
   derive from historical use of the term `accumulator' (and not,
   actually, from `arithmetic').  Confusingly, though, an `A'
   register name prefix may also stand for `address', as for
   example on the Motorola 680x0 family.  2. A register being used for
   arithmetic or logic (as opposed to addressing or a loop index),
   especially one being used to accumulate a sum or count of many
   items.  This use is in context of a particular routine or stretch
   of code.  "The FOOBAZ routine uses A3 as an accumulator."
   3. One's in-basket (esp. among old-timers who might use sense 1).
   "You want this reviewed?  Sure, just put it in the accumulator."
   (See {stack}.)