The document discusses different addressing modes used in computer instructions. It explains that the addressing mode specifies how the operands are chosen during program execution. Some key addressing modes are direct, indirect, register, register indirect, and relative addressing. The addressing mode determines the effective address, which is the actual memory location of the operand.

1. ADDRESSING MODES

15. NUMERICAL EXAMPLE PC=200 R1=400 XR=100 AC ADDRESS MEMORY 200 201 202 399 400 500 600 702 800 300 325 900 800 700 450 NEXT INSTRUCTION ADDRESS=500 LOAD TO AC MODE