Instruction Address Register


instruction address register

[in′strək·shən ə¦dres ′rej·ə·stər] (computer science) A special storage location, forming part of the program controller, in which addresses of instructions are stored in order to control their sequential retrieval from memory during the execution of a program.

Instruction Address Register

(IAR) The IBM name for program counter.

The IAR can be accessed by way of a supervisor call insupervisor state, but cannot be directly addressed inproblem state.