COMS 361 Computer Organization Title: Architecture, Organization and Abstraction Date: 08/31/2004 Lecture Number: 2

Announcements Homework 1 Due next Tuesday 9/07/04

Review Rules of the game Any questions? Course Overview

Outline Computer System Organization Instruction Set Architecture (ISA) Hardware Set Architecture (HSA) Computer Organization

Computer System Organization Common desktop computer system 7

Computer System Organization Open up the box and see what is inside 7

Computer System Organization Focus on the Motherboard What is all that “stuff”? 7

Abstractions Use abstraction to manage complexity Focus on pertinent information Suppress unnecessary detail 9

Computer System Organization “Five classic components” Processor Input Control Datapath Output Memory 1001010010110000 0010100101010001 1111011101100110 7

Computer System Operation Executing Programs - the “fetch/execute” cycle Processor fetches instruction from memory Processor executes “machine language” instruction next instr Load Data Perform Calculation Store Results OK, but how do we write useful programs using these instructions? Processor Control Datapath 1001010010110000 0010100101010001 1111011101100110 Memory Address 1001010010110000 Instruction 8

Computer System Operation The active part of the computer is the processor Also called the Central Processing Unit Consists of two basic units The datapath For arithmetic operations Control Operates the data path Makes memory function Coordinates I/O activity 8

Under the Hood: 4004 2300 transistors 46 instructions 0.75 MHz Intel 4004, 1971, the worlds first commercial microprocessor 2300 transistors 46 instructions 0.75 MHz

Under the Hood: The Pentium 4 Die Photo Package 10’s of millions of transistors

Under the Hood: The Pentium 4

High-level Languages High-Level Programming languages are abstractions High-Level Language (C) c = a + b; Compiler Assembly Language add R8,R1,R2 Assembler Machine Language 00000000001000100100000000100000

Instruction Set Architecture The most important abstraction of computer design Software Compiler Application Programs Operating System Application Instruction Set Architecture Interface between SW & HW Logic - gates, state machines, etc. Circuit - transistors, etc. Layout - mask patterns, etc. Hardware Processor I/O System 12

Instruction Set Architecture Standardizes instructions, machine language bit patterns, etc, … Advantage: Allows for different implementations of the same architecture Disadvantage: New features are added to older designs Sometimes prevents new innovations

Instruction Set Architecture Modern instruction set architectures: 80x86/Pentium/K6 PowerPC DEC Alpha SPARC HP MIPS

Top 5 Reasons to Study MIPS 5. It’s in the book 4. It’s used in many applications 3. Learning its architecture and implementation exposes you to important concepts 2. It’s relatively simple and easy to implement (compared to other architectures) 1. Ideas presented using MIPS generalize to other architectures (even the 80x86!)

Computer Architecture Two main components Instruction set architecture (ISA) Hardware set architecture (HSA)

Instruction Set Architecture (ISA) Determines processors computational characteristics Defines the instructions and resources of a processor Instruction set (collection of all operations possible in the machine-language) The processor memory All program accessible registers Instruction set Number of bits representing various data types I/O mechanisms Memory addressing techniques

Hardware System Architecture (HSA) Operational components and their interconnections The implementation of the architectural specifications Determines machine efficiency The arithmetic and logic unit (ALU) The storage systems I/O systems Address and memory busses

ISA Allows Backwards Compatibility A program written for an 8086 processor will still execute on the latest Pentium processor ISA allows for families of processors Different prices and capabilities

Distinguish Computer Architecture Computer Organization Definition of the ISA Computer Organization Implementation of the HSA

Computer Organization Individual operational units and their interconnections Hardware details not visible to the programmer Control signals Interfaces between the computer and peripherals Types of memory used L1 and L2 cache Virtual memory

Computer Organization Choice of providing a multiply instruction Architectural or organizational issue? Choice of separate hardware or iterative addition in the ALU for a multiply instruction

VLSI Trends: Moore’s Law In 1965, Gordon Moore predicted that transistors would continue to shrink, allowing: Doubled transistor density every 24 months Doubled performance every 18 months History has proven Moore right But, is the end in sight? Physical limitations Economic limitations Gordon Moore Intel Co-Founder and Chairmain Emeritus

Microprocessor Trends (Log Scale)

Microprocessor Trends (Intel) 17

Microprocessor Trends I2M Alpha (R.I.P) P4N, G5

Microprocessor Trends (Log Scale) I2M Alpha (R.I.P) P4N, G5 G4

DRAM Memory Trends (Log Scale)

Performance Trends Vax 11/780

Summary - Technology Trends Processor Logic capacity increases ~ 30% per year Clock frequency increases ~ 20% per year Cost per function decreases ~20% per year Memory DRAM capacity: increases ~ 60% per year (4x every 3 years) Speed: increases ~ 10% per year Cost per bit: decreases ~25% per year Disk Storage capacity increases ~60% per year