Introduction to computers Classifications of computers (1)By nature (2)By purpose (3)By size Generations(5)

Computers

Digital ComputersDigital Computers Analog ComputersAnalog Computers

Hybrid computersHybrid computers

Classification by nature

Digital Computers

Use digits specially binary digits (0, 1) to represent data

Examples:

Personal computers such as Laptops and Desktops, etc

Computer Classification

Classification by nature

Analog Computers

Use physical magnitudes as voltage and pressure instead of digits

Examples:

Thermometers, voltmeters, speed measuring meters, etc

Computer Classification

Classification by nature

Hybrid Computers

Combination of both the analogue and digital computers

Examples: A computer that maintain temperature in a burner of a production plant

Computer Classification

Classification by nature

Computer Classification

Classification by Purpose

Special purpose Special purpose computerscomputers

General purpose General purpose computerscomputers

Computers

Special purpose computers

› Designed for a special job only

› Examples: Computers used in digital watches, pocket calculators, point of sales, etc

Computer Classification

Classification by Purpose

General Purpose computers

› Design to solve wide variety of problems

› Examples: A personal computer used in an office or at home

Computer Classification

Classification by Purpose

Can a general purpose computer Can a general purpose computer be converted to a special purpose computer ?be converted to a special purpose computer ?

By size

Mainframe

Minicomputers

Microcomputers

Supercomputer

Mainframe computer

› A large computer › has enormous input, process, output and

storage capacities › hundreds of terminals connected › hundreds of users can work simultaneously

Computer Classification

Classification by size

Mini computer

A smaller version of Mainframes

Computer Classification

Classification by size

Computer Classification

Classification by size

MicrocomputerMicrocomputer

A smaller computerA smaller computer

available for only one user at any time available for only one user at any time

The central processing unit is embedded The central processing unit is embedded in a single chip - in a single chip - microprocessormicroprocessor

Examples: personal computers; Examples: personal computers; Laptops, desktopsLaptops, desktops

The First generation

The Second Generation

The Third Generation

The Fourth Generation

The Fifth Generation

1942-1955 Vacuum Tube

› Heat› Burnout

Machine language

Magnetic core memory

Storage› Punched cards› Tape (1957)

Characteristics of 1st Generation Computers Computers big and clumsy Electricity consumption is high Electric failure occurred regularly  - computers not very reliable Large air conditioners was necessary because the computers generated heat Batch processing

1942-1955

1942-1955

1955-1964 Transistor

› Smaller› No warm-up time› Less energy› Less heat› Faster› More reliable

Storage› Removable disk pack

(1954)› Magnetic tape

Programming languages› Assembly language› FORTRAN (1954)› COBOL(1959)

Used primarily by business, university, government

Computers became smaller   Generate less heat Electricity consumption lower More reliable and faster  Core memory developed Magnetic tapes and disks used First operating systems developed A new processing method was needed. Time-sharing (processing

technique)

1955-1964

1964-1975 Integrated Circuit

› Electronic circuit on small silicon chip

› Reliability› Compactness› Low cost› Inexpensive –

mass-produced

1. Computers smaller, faster and more reliable

2. Power consumption lower

3. High-level languages appeared

1975-1989 Microprocessor

› General-purpose processor on a chip

Explosive growth› Digital watches› Pocket

calculators› Personal

computers› Cars› Copy machines› Television sets

• Integrated circuits, smaller and faster

• Micro computer series such as IBM and APPLE developed

• Portable computers developed • Great development in data

communication

• Different types of secondary memory with high storage capacity and fast access

developed

1975-1989

1989-Present Large capacity of

main memory, hard disk, optical disk.

Notebook Powerful desktop

P.C and workstation Very powerful

mainframe systems

Internet World wide web

(www) ,multimedia applications

Portable computers, more powerful ,cheaper ,reliable and easy to use.

1989 - today