Intro to Architecture & Organization

Abstractions Need to make insanely complex hardware easier to work with:

Levels of a Computer Computer levels: Abstractions used to build higher levels

ISA Architecture: what a computer can do ISA : Instruction Set Architecture – the instructions a machine can perform

Organization Organization: how a computer implements ISA Also called Microarchitecture

von Neumann Model Basic architecture of most modern computers: A central processing unit (CPU) A main memory system An I/O system Main memory stores Data Instructions

Von Neumann Model Fetch – Decode – Execute cycle Fetch: Program counter identifies instruction to fetch from memory

Von Neumann Model Fetch – Decode – Execute cycle Decode: Control unit activates hardware based on exact instruction

Von Neumann Model Fetch – Decode – Execute cycle Execute: Work is executed

Von Neumann Bottleneck Issue: All traffic passes through CPU

Von Neumann Bottleneck Modern Von Neumann One+ system busses

Memory Memory Model

Memory Memory Model

A Program A problem: And program 

Functional View Running any program: Stored_program_machine Point to the first instruction REPEAT Read the instruction at the memory location pointed at Point to the next instruction Decode the instruction read from memory Execute the instruction UNTIL instruction == stop End

Implementation 3 Op P  Q + R