In
computer engineering, a registerâmemory architecture is an
instruction set architecture that allows operations to be performed on (or from)
memory, as well as
registers.[1] If the architecture allows all operands to be in memory or in registers, or in combinations, it is called a "register plus memory" architecture.[1]
In a registerâmemory approach one of the operands for operations such as the ADD operation may be in memory, while the other is in a register. This differs from a
loadâstore architecture (used by
RISC designs such as
MIPS) in which both operands for an ADD operation must be in registers before the ADD.[1]
An example of register-memory architecture is
Intel x86.[1] Examples of register plus memory architecture are:
PDP-11, which supports memory or register source and destination operands for most two-operand integer operations;[5]
VAX, which supports memory or register source and destination operands for binary integer and floating-point arithmetic;[6]
Motorola 68000 series, which supports integer arithmetic with a memory source or destination, but not with a memory source and destination. However, the 68000 can move data memory-to-memory with nearly all addressing modes.[7]