1. Introduction to Computers

2. Chapter Goals 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
List the basic components of a computer system
Understand what a Computer Program is
List the Programming Life-Cycle Phases 25

3. 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 3

4. 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 6

5. Early History of Computing
Ada Lovelace
First Programmer
Alan Turing
Turing Machine, Artificial Intelligence Testing
Harvard Mark I, ENIAC, UNIVAC I
Early computers launch new era in mathematics, physics, engineering and economics 7

6. 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 8

7. 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 9

8. 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 10

9. Fourth Generation Hardware (1971-?)
Large-scale Integration
Great advances in chip technology
PCs, the Commercial Market, Workstations
Personal Computers were developed as new companies like Apple and Atari came into being. Workstations emerged. 11

10. Parallel Computing and Networking
Computers rely on interconnected central processing units that increase processing speed.
Networking
ARPANET and LANs  Internet 12

11. First Generation Software (1951-1959)
Machine Language
Computer programs were written in binary (1s and 0s)
Assembly Languages and translators
Programs were written in artificial programming languages and were then translated into machine language
Programmer Changes
Programmers divide into application programmers and systems programmers 13

12. Second Generation Software (1959-1965)
High Level Languages
Use English-like statements and make programming easier.
Fortran, COBOL, Lisp are examples.
High-Level
Languages
Assembly Language
Machine
Language 14

13. Third Generation Software (1965-1971)
Systems Software
utility programs,
language translators,
and the operating system, which decides which
programs to run and when.
Separation between Users and Hardware
Computer programmers began to write programs to be used by people who did not know how to program 15

14. Third Generation Software (1965-1971)
Application Package
Systems Software
High-Level Languages
Assembly Language
Machine Language 16

15. Fourth Generation Software (1971-1989)
Structured Programming
Pascal, C, C++
New Application Software for Users
Spreadsheets, word processors, database management systems 17

16. Fifth Generation Software (1990- present)
Microsoft
The 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 18

17. Applications Programmer Domain-Specific Programs
Computing as a Tool
Programmer / User
Systems Programmer
(builds tools)
Applications Programmer
(uses tools)
Domain-Specific Programs
User with No
Computer Background 20

18. Computing as a Discipline
What can be (efficiently) automated?
Four Necessary Skills
Algorithmic Thinking
Representation
Programming
Design 21

19. Computing as a Discipline
What do you think?
Is Computer Science a mathematical, scientific, or engineering discipline? 22

20. Systems Areas of Computer Science
Algorithms and Data Structures
Programming Languages
Architecture
Operating Systems
Software Methodology and Engineering
Human-Computer Communication 23

21. Application Areas of Computer Science
Numerical and Symbolic Computation
Databases and Information Retrieval
Artificial Intelligence and Robotics
Graphics
Organizational Informatics
Bioinformatics 24

22. Computer Components-- Hardware

23. Memory Unit
is an ordered sequence of storage cells, each capable of holding a piece of information
each cell has its own unique address
the information held can be input data, computed values, or your program instructions.

24. Memory Unit

25. RAM and ROM RAM stands for Random Access Memory
Inherent in the idea of being able to access each location is the ability to change the contents of each location
ROM stands for Read Only Memory
The contents in locations in ROM cannot be changed
RAM is volatile, ROM is not
This means that RAM does not retain its bit configuration when the power is turned off, but ROM does

26. Secondary Storage Devices
Because most of main memory is volatile and limited, it is essential that there be other types of storage devices where programs and data can be stored when they are no longer being processed
Secondary storage devices can be installed within the computer box at the factory or added later as needed

27. Magnetic Tape
The first truly mass auxiliary storage device was the magnetic tape drive

28. Magnetic Disks
A read/write head travels across a spinning magnetic disk, retrieving or recording data

29. Compact Disks
A CD drive uses a laser to read information stored optically on a plastic disk
CD-ROM is Read-Only Memory
DVD stands for Digital Versatile Disk

30. Peripherals
are input, output, or auxiliary storage devices attached to a computer
Input Devices include keyboard and mouse.
Output Devices include printers, video display, LCD screens.
Auxiliary/Secondary Storage Devices include disk drives, scanners, CD-ROM and DVD-ROM drives, modems, sound cards, speakers, and digital cameras.

31. Central Processing Unit
has 2 components to execute program instructions
Arithmetic/Logic Unit performs arithmetic operations, and makes logical comparisons.
Control Unit controls the order in which your program instructions are executed.

32. Flow of Information
The parts are connected to one another by a collection of wires called a bus

33. The Fetch-Execute Cycle
Fetch the next instruction
Decode the instruction
Get data if needed
Execute the instruction

34. The Fetch-Execute Cycle