accumulator

[uh-kyoo-myuh-ley-ter] /əˈkyu myəˌleɪ tər/
noun
1.
a person or thing that accumulates.
2.
a register or electric device on an arithmetic machine, as an adding machine, cash register, or digital computer, that receives a number and produces and stores the results of arithmetic operations of the given number with other numbers.
3.
British. a storage battery or storage cell.
4.
an apparatus that stores fluid at approximately the working pressure of the hydraulic or pneumatic system in which it will be employed, so that a supply of fluid is always immediately available to the system.
5.
Machinery. (in a boiler) a vessel for storing hot fluid, ready to flash into steam.
6.
Hydraulics. a vessel in which air is trapped and compressed by the liquid, thus storing energy to supply liquid under pressure when the demand of the system is greater than the capacity of the pump.
Origin
1685-95; < Latin accumulātor, equivalent to accumulā(re) to heap up (see accumulate) + -tor -tor
British Dictionary definitions for accumulator

accumulator

/əˈkjuːmjʊˌleɪtə/
noun
1.
Also called battery, storage battery. a rechargeable device for storing electrical energy in the form of chemical energy, consisting of one or more separate secondary cells
2.
(horse racing, Brit) a collective bet, esp on four or more races, in which the stake and winnings on each successive race are carried forward to become the stake on the next, so that both stakes and winnings accumulate progressively so long as the bet continues to be a winning one
3.
  1. a register in a computer or calculator used for holding the results of a computation or data transfer
  2. a location in a computer store in which arithmetical results are produced
accumulator in Technology

processor
In a central processing unit, a register in which intermediate results are stored. Without an accumulator, it would be necessary to write the result of each calculation (addition, multiplication, shift, etc.) to main memory and read them back. Access to main memory is slower than access to the accumulator which usually has direct paths to and from the arithmetic and logic unit (ALU).
The canonical example is summing a list of numbers. The accumulator is set to zero initially, each number in turn is added to the value in the accumulator and only when all numbers have been added is the result written to main memory.
Modern CPUs usually have many registers, all or many of which can be used as accumulators. For this reason, the term "accumulator" is somewhat archaic. 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, memory location or variable 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."
[Jargon File]
(1999-04-20)