Accumulator machine

Accumulator machines

An accumulator machine, also called a 1-operand machine, or a CPU with accumulator-based architecture, is a kind of CPU where, although it may have several registers, the CPU mostly stores the results of calculations in one special register, typically called "the accumulator". Almost all early computers were accumulator machines. Some had two accumulators with distinct names, some had more than two registers called accumulators, referred to by numbers. Then, with the introduction of microprocessors, accumulator architectures were again popular with the MOS 6502 being a notable example. Many 8-bitmicrocontrollers that are still popular as of 2014, such as the PICmicro and 8051, are accumulator-based machines.