What is the difference between in-register and in-memory evaluation?
These terms refer to the way instruction operands are evaluated. The ’88 Redcode standard ICWS’88 is unclear about whether a simulator should “buffer” the result of A-operand evaluation before the B-operand is evaluated. Simulators that do buffer are said to use in-register evaluation, those that don’t, in-memory evaluation. ICWS’94 clears this confusion by mandating in-register evaluation. Instructions that execute differently under these two forms of evaluation are MOV, ADD, SUB, MUL, DIV and MOD where the effective address of the A-operand is modified by evaluation of the B-operand.
