1. Introduction

1.1. Introduction

• CPU performance factors
  • Instruction count
    • Determined by ISA and compiler
  • CPI and Cycle time
• Simple subset, shows most aspects
  • Memory reference : lw, sw
  • Arithmetic/logical : add, sub, or, slt
  • Control transfer : beq, j

1.2. Introduction Execution

1. Instruction fetch → PC가 가르키고 있는 instruction을 memory로부터 읽어 옴
   1. PC → instruction memory, fetch instruction
2. Instruction decoding and register prefetch → register를 읽음
   1. Decodes instruction → 어떤 instruction인지 해석 ⇒ op code로 파악
   2. Register number → register file, read registers
3. depending on instruction class
   1. Use ALU to calculate
      1. Arithmetic result
      2. Memory address for load/store → memory address 계산하기 위해
      3. Branch target address → branch target address를 계산하기 위해
   2. Access data memory for load/store
   3. PC ← target address or PC + 4

1.3. CPU Overview

1.4. Multiplexers

• MUX를 사용

1.5. Control

2. Logic Design Conventions

2.1. Logic Design Basics

• Information encoded in binary
  • Low voltage = 0, High voltage = 1
  • One wire per bit
  • Multi-bit data encoded on multi-wire buses
• Combinational element

  • Output is a function of input

  • input이 바로 output에 전달

    ex) a + b = c