• Also known as Machine Codes
  • Bit String, which is passed to CPU, gets translated to carry out Operation
  • Doesn’t specify which CPU Datapath does what, just specify what outputs are expected with a given input
  • The instruction lifecycle can be broken down into Pipeline Stages



In MIPS, it is 6-bits, so total 2^6 64 different arrangements.


Fixed-length Instruction

Variable-length Instruction

Branch Instruction


Single Instruction Multiple Data

  • This allows one Instruction to operate on multiple data at once and have multiple outputs essentially
  • This can reduce the number of instructions in a program significantly, and have more data processed without the involvement of the inefficient Main Memory

Expanding Opcode Scheme

  • The Opcode in an Instruction can be extended to accommodate additional instructions in the future without changing the basic format of the instruction set