Processor Architecture

1
Processor Architecture

• Kieran Mathieson

2
Outline

• Memory
• CPU Structure
• Design a CPU
• Programming
• Design Issues

3
Memory
4
Memory

• Made up of bits
• Fixed word (cell) size
• Cells contain instructions and data
• Each word has an address
• Flat memory model
• Segmented memory model

5
CPU Structure
6
CPU Structure

• Fetch/execute cycle
• Registers used to operate on data
• Scratchpad
• Special-purpose registers instruction register,
  instruction pointer, program status word
• Control unit interprets instructions
• Opens and closes the right gates to move data
  around
• ALU performs computations

7
Design a CPU

• Decimal for simplicity
• 1,000 word of RAM - each 4 digits long
• 10 registers numbered 0 to 9
• Special-purpose registers - instruction register,
  instruction pointer
• Create an instruction set
• Input/output
• Move data between registers and memory
• Computation
• Branching

8
Program

• Write a program to input two numbers, add them,
  and output
• Write a program to add up some numbers the user
  inputs
• The user specifies how many numbers to add

9
What It Looks Like
10
CPU Design Issues

• Word size
• CISC vs. RISC
• Clock speed
• Electrical properties heat, circuit length,
  fabrication

11
Outline

• Memory
• CPU Structure
• Design a CPU
• Programming
• Design Issues