Chapter 01

Chapter 1
The Big Picture

Chapter Goals
• Describe the layers of a computer system
• Describe the concept of abstraction and its
relationship to computing
• Describe the history of computer hardware and
software
• Describe the changing role of the computer user
• Distinguish between systems programmers and
applications programmers
• Distinguish between computing as a tool and
computing as a discipline
2
25
Computing Systems
Computing systems are dynamic and highly

interactive!
What is the difference between hardware

and software?
3
2
Computing Systems
Hardware The physical elements of a

computing system (printer, circuit boards,
wires, keyboard…)
Software The programs that provide the

instructions for a computer to execute
4
3
Layers of a Computing System
5
4
Abstraction
Abstraction A mental model that removes

complex details
This is a key concept. Abstraction will
reappear throughout the text – be sure you
understand it!
6
5
Internal View
7
Abstract View
8
History
9
Early History of Computing
Abacus
An early device to record numeric values
Blaise Pascal
Mechanical device to add, subtract, divide & multiply
Joseph Jacquard
Jacquard’s Loom, the punched card
Charles Babbage
Analytical Engine
10
6
Early History of Computing
Ada Lovelace
First Programmer, the loop
Alan Turing
Turing Machine, Artificial Intelligence Testing
11
7
The First Computers
Harvard Mark I, ENIAC, UNIVAC I

Early computers launch new era in mathematics,
physics, engineering and economics
“Where a calculator on the ENIAC is equipped with

18,000 vacuum tubes and weighs 30 tons,
computers in the future may have only 1,000
vacuum tubes and perhaps weigh 1.5 tons.”
(Popular Mechanics, 1949)
12
First Generation Hardware
(1951-1959)
Vacuum Tubes
Large, not very reliable, generated a lot of heat
Magnetic Drum
Memory device that rotated under a read/write head
Card Readers  Magnetic Tape Drives

Sequential auxiliary storage devices
13
8
Second Generation Hardware
(1959-1965)
Transistor
Replaced vacuum tube, fast, small, durable, cheap
Magnetic Cores
Replaced magnetic drums, information available
instantly
Magnetic Disks
Replaced magnetic tape, data can be accessed directly
14
9
Third Generation Hardware
(1965-1971)
Integrated Circuits
Replaced circuit boards, smaller, cheaper, faster, more
reliable
Transistors
Now used for memory construction
Terminal
An input/output device with a keyboard and screen
15
10
Fourth Generation Hardware
(1971-?)
Large-scale Integration
Great advances in chip technology
PCs, the Commercial Market, Workstations

Personal Computers and Workstations emerge
New companies emerge: Apple, Sun, Dell …
Laptops
Everyone has his/her own portable computer
16
11
Parallel Computing
Parallel Computing
Computers rely on interconnected central processing
and/or memory units that increase processing speed
“Real concurrency -- in which one program

actually continues to function while you call up
and use another -- is more amazing but of small
use to the average person. How many programs
do you have that take more than a few seconds
to perform any task?”
New York Times, 1989
17
12
Networking
Networking
Ethernet connects small computers to share resources
File servers connect PCs in the late 1980s
ARPANET and LANs  Internet
“Transmission of documents via telephone wires

is possible in principle, but the apparatus
required is so expensive that it will never
become a practical proposition.”
Dennis Gabor, 1962
18
12
First Generation Software
(1951-1959)
Machine Language
Computer programs written in binary (1s and 0s)
Assembly Languages and Translators

Programs written using mnemonics, which were
translated into machine language
Programmer Changes
Programmers divide into two groups: application
programmers and systems programmers
19
13
Assembly/Machine
Systems programmers Applications programmers

write the assembler use assembly language to
(translator) solve problems
20
Second Generation Software
(1959-1965)
High-level Languages
English-like statements made programming easier:
Fortran, COBOL, Lisp
Systems
programmers
write translators for
high-level languages
Application
programmers
use high-level
languages to
solve problems
21
14
Third Generation Software
(1965-1971)
Systems Software
Utility programs
Language translators
Operating system, which decides which programs
to run and when
Separation between Users and Hardware

Computer programmers write programs to be used by
general public (i.e., nonprogrammers)
22
15
Third Generation Software
(1965-1971)
23
16
Fourth Generation Software
(1971-1989)
Structured Programming
Pascal
C++
New Application Software for Users

Spreadsheets
Word processors
Database management systems
24
17
Fifth Generation Software
(1990- present)
Microsoft
Windows operating system and other Microsoft application
programs dominate the market
Object-Oriented Design
Based on a hierarchy of data objects (i.e. Java)
World Wide Web

Allows easy global communication through the Internet
New Users
Today’s user needs no computer knowledge
25
18
Computing as a Tool
Programmer / User
Systems Programmer Applications Programmer

(builds tools) (uses tools)
Domain-Specific Programs
User with No
26 Computer Background
20
Computing as a Discipline
What can be (efficiently) automated?
Four Necessary Skills

• Algorithmic Thinking
• Representation
• Programming
• Design
27
21
Computing as a Discipline
What do you think?
Is Computer Science a mathematical,

scientific, or engineering discipline?
28
22
Examples of Systems Areas
• Algorithms and Data Structures

• Programming Languages
• Architecture
• Operating Systems
• Software Engineering
• Human-Computer Communication
29
23
Examples of Application Areas
• Numerical and Symbolic Computation

• Databases and Information Retrieval
• Intelligent Systems
• Graphics and Visual Computing
• Net-Centric Computing
• Computational Science
30
24
Ethical Issues
The Digital Divide

What is it?
How does it affect you?
What is computer literacy for
your sister, the musician?
your brother, the doctor?
your sister, the kindergarten teacher?
Is it important to try to bridge the digital divide?
31
Who am I?
Can you list three items on my resume?
32
Do you know?
What computer company was launched in a

garage?
What branch of mathematics is being used in

terrorist detection?
What is Room to Read?
When and where were the first CS Departments

formed?
33

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Chapter 1

The Big Picture

Computing systems are dynamic and highly

What is the difference between hardware

Hardware The physical elements of a

Software The programs that provide the

Abstraction A mental model that removes

Harvard Mark I, ENIAC, UNIVAC I

“Where a calculator on the ENIAC is equipped with

Card Readers  Magnetic Tape Drives

PCs, the Commercial Market, Workstations

“Real concurrency -- in which one program

ARPANET and LANs  Internet

“Transmission of documents via telephone wires

Assembly Languages and Translators

Systems programmers Applications programmers

Separation between Users and Hardware

New Application Software for Users

World Wide Web

Systems Programmer Applications Programmer

What can be (efficiently) automated?

Four Necessary Skills

What do you think?

Is Computer Science a mathematical,

• Algorithms and Data Structures

• Numerical and Symbolic Computation

The Digital Divide

Can you list three items on my resume?

What computer company was launched in a

What branch of mathematics is being used in

What is Room to Read?

When and where were the first CS Departments

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