Chapter 1

Computer Systems

Why study Computer Architecture?

ExamplesWeb Browsing - how does the browser access pages from a server? How can we create graphics that can be loaded more quickly?

Configuring Systems - How good is the system? What kind of performance can one expect for desired applications? What additional information is needed to make a more informed decision?

Example - Terminology

Java Example

Java is best described by a client-server model. Program is compiled on the server into a set of binary code words that represent a generic, stack-based machine language. On the server, the binary code words are interpreted, then executed on a virtual machine. Java uses a multi-threaded paradigm, where new threads are easily created by the programmer.

Computer Professional

Deeper understanding of the computer itself - rather than just a user

Understanding inherent operations of a computer promotes effectiveness in its use

User

Awareness of the capabilities and limitations of the computer system

An understanding of OS commands and internal operations

Improved communication with others

Programmer

Write more efficient programs Know why some languages are

more efficient than others Understand system errors more

clearly Intermix machine language and

higher level language code

Systems Analyst

Be able to fix the appropriate system to the application

Supports technical specification of desired system

Learn tradeoffs of different file system formats

Learn requirements for building an internet

Important Fact

“In an era where technology changes very rapidly, the fundamental architecture of the computer rests on a solid foundation that has changed only slightly and gradually over the last 50 years” - Englander

Solid Foundation Has Not Changed

Von Neumann’s Architecture - ‘45 Unix - late ‘60s IBM/360 Machine Language - ‘64

identical to today’s IBM/390 Internet - 25 years old and same

protocols and paradigms

Computer Application(compare w/WP)

Input-Output-Processing-Storage

What is Computer Architecture?

Data• fundamental representation of facts and

observations Hardware

• processes data by executing instructions, moves data between storage, input and output

Software• instructions executed by the hardware

Communications• sharing data and processing among different

computers

Data Component

Text Numbers Pictures Sound Video Animation Charts

Much greater variety in types available today. This component actually has changed in format, but not how it is used.

(We will discuss more in Ch 3)

A Typical Computer SystemHardware

Software Component

Systems Software• Operating Systems, Utilities

Applications Software• fills a business need or solves a

business problem

An Overview

Application ProgramsUtilities

Operating SystemComputer Hardware

End User

Programmer

O/S Designer

Simplified OS Diagram

Communications Component

Computers do not operate alone LAN or WAN Hardware and Software

Components EQ - communication channels

(wire, fiber optics, wireless,…) EQ - protocols

In the Beginning - ENIACElectronic Numerical Integrator and Calculator

• Publicly announced in 1946 • First operational electronic, general purpose machine• Military use • 80 ft long, 8.5 ft high, 2 ft wide• 18,000 vacuum tubes• Programmable

Observation

Whereas… the ENIAC is equipped with 18,000 vacuum tubes and weighs 30 tons, computers in the future may have 1,000 vacuum tubes and perhaps weigh just 1 1/2 tons.

------ Popular Mechanics, March 1949

John von Neumann Principles - 1945

Stored Program Concept Binary Processing of Data Memory is addressed linearly Memory is addressed without

regard to content Memory holds programs and data

Overview of Englander’s Text

Part 1 - Data• Number systems, how other forms of data

are stored Part 2 - Hardware

• CPU, memory, instruction sets, I/O devices, storage devices

Part 3 - Systems Software• Operating Systems, User Interface, File

Management Part 4 - Networks and Data Communications