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

2. Announcements
Homework 1
Due next Tuesday 9/07/04

3. Review
Rules of the game
Any questions?
Course Overview

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

5. Computer System Organization
Common desktop computer system 7

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

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

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

9. Computer System Organization
“Five classic components”
Processor
Input
Control
Datapath
Output
Memory 7

10. 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
Memory
Address
Instruction 8

11. 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

12. 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

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

14. Under the Hood: The Pentium 4

15. 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

16. 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

17. 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

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

19. 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!)

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

21. 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

22. 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

23. 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

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

25. 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

26. 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

27. 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

28. Microprocessor Trends (Log Scale)

29. Microprocessor Trends (Intel)17

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

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

32. DRAM Memory Trends (Log Scale)

33. Performance Trends
Vax 11/780

34. 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