base/displacement

A machine architecture that runs programs no matter where they reside in memory. Addresses in a machine language program are displacement addresses, which are relative to the beginning of the program. At runtime, the hardware adds the address of the current first byte of the program (base address) to each displacement address and derives an absolute address for execution.

All modern computers use some form of base/displacement or offset mechanism in order to to run multiple programs in memory at the same time.