Battery (register processor)

A battery (processor register) is a register in which the immediate results of arithmetic and logical instructions are stored. Alternative methods for storing the result are the use of general purpose registers or RAM.

A microprocessor with a battery architecture or a 1-operand machine is different in that even if it has several registers, the result of most operations is stored in a special register called the “battery”. This simplifies both the implementation of the architecture and reduces the size of the machine code. Historically, almost all of the first microprocessors were battery-powered machines, and now many popular single-chip microcontrollers (68HC12 ^[P] , PIC, 8051) are battery-powered machines.

Modern CPUs are usually 2 and 3 operand machines - in which additional operands indicate between which of the general purpose registers are performed calculations.

A processor can have several batteries: in 8051 there are two, the main A and the secondary B, and the second is used during multiplication and division.