OPCODE, OPERAND, Instruction Set & Data Transfer Categories

• OPCODE (Operation Code): Specifies operation, e.g., MOV, ADD, encoded as binary. In MOV A,#55H, MOV opcode is 74H.
• OPERAND: Data/address on which opcode acts, e.g., A, #55H, R0.

Instruction Set: Entire collection of opcodes a CPU can execute (8051 has 111 instructions).

3 Categories of Data Transfer:

1. Immediate/Internal → Register: MOV A,#data, MOV R0,A
2. Memory ↔ Register: MOVX A,@DPTR, MOVC, MOV A,@R0
3. Stack/Exchange: PUSH, POP, XCH, XCHD
   (Also grouped as CPU↔RAM, CPU↔SFR/Port, CPU↔External.)