CISC360 Lecture Notes - Lecture 3: Operand, Opcode, Program Counter

• School: University of Delaware
• Department: Computer and Information Sciences
• Course: CISC360
• Professor: Sunita Chandrasekaran

Document Summary

1: memory addressing, addressing modes, types and size of operands, operations, control flow instructions, encoding isa, operations. 3 instruction formats, all 32 bits wide: op -opcode rs -register address 1 rt -register address 2 rd -destination register shamt -shift amount (for shift instructions) funct -function immediate -16 bit offset target address -address of next instruction. Base (displacement addressing): operand is at the memory location whose address is the sum of a register and a 16-bit constant contained within the instruction. Immediate addressing: operand is a 16-bit constant contained within the instruction. Pc-relative addressing: address of the operand is the sum of the pc (program counter) and a 16-bit constant contained within the instruction. The size of immediate and displacement values affect the length of the instruction because they have to be stored in the instruction itself. When the condition is met, jump occurs, pc incremented to point to the next instruction.