|n.||1.||One who, or that which, accumulates, collects, or amasses.|
|2.||(Mech.) An apparatus by means of which energy or power can be stored, such as the cylinder or tank for storing water for hydraulic elevators, the secondary or storage battery used for accumulating the energy of electrical charges, etc.|
|3.||A system of elastic springs for relieving the strain upon a rope, as in deep-sea dredging.|
|Noun||1.||accumulator - a person who is employed to collect payments (as for rent or taxes)|
|2.||accumulator - a voltaic battery that stores electric charge|
Synonyms: storage battery
|3.||accumulator - (computer science) a register that has a built-in adder that adds an input number to the contents of the accumulator|
Synonyms: accumulator register
|(processor)||accumulator - 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.