Definition

1. Noun:
   • (Computer Science) A special storage register within a central processing unit (CPU): An accumulator register is a type of register that contains a built-in adder (or arithmetic logic unit). Its primary function is to hold an intermediate arithmetic or logic result. It "accumulates" a total by having an input number added to (or otherwise combined with) the value currently stored in the register.

Usage Examples

• Noun:
  • The processor's accumulator register holds the sum after each addition operation.
  • In early computer architectures, most arithmetic operations involved the accumulator register.
  • The value in the accumulator register is incremented by the input from the data bus.

Advanced Usage

• Historical Context: In many early and simple CPU designs, the accumulator register was the primary, and sometimes the only, register for performing calculations. This architectural style is known as an accumulator machine.

  • In the 6502 microprocessor, the accumulator register was central to its operation.

• Modern Context: While modern CPUs have multiple general-purpose registers reducing the singular role of a dedicated accumulator, the term is still used in low-level programming and digital circuit design to describe a register that accumulates a sum or result.

  • The digital signal processor uses an accumulator register for summing the products in a filter calculation.

Variants and Related Words

• Accumulator (n): Often used as a shortened, informal term for "accumulator register."

  • The result is stored in the accumulator.

• Register (n): A small, high-speed storage location within the CPU.

• Adder (n): A digital circuit that performs addition of numbers.

Synonyms

• Accumulator (when context clearly refers to a CPU register).
• A-register (a common abbreviation in assembly language and computer architecture).

Related Phrases/Concepts

• "To load the accumulator": A common instruction meaning to place a value from memory into the accumulator register.

  • The program must load the accumulator with the first data value.

• "To store from the accumulator": An instruction to save the value from the accumulator register back to memory.

  • The final result is stored from the accumulator to the output location.

Noun

1. (computer science) a register that has a built-in adder that adds an input number to the contents of the register