Introduction to the Computer - Fundamentals of computers- A Definition

Fundamentals of Computer- Definition of Computer-A computer(computer system) is an electronic device capable of manipulating numbers and symbols under the control of a set of instructions known as a computer.

Computer programs direct the computer to solve particular problems and display results.
Computer programs are written using programming languages such as BASIC, FORTRAN, COBOL, PASCAL, C, C++, JAVA, ALGOL, and so on.

Methodology of usage (computer system):

To perform any task using a computer (computer system), programs are unavoidable. These programs are written to get the desired result considering the mathematical method and logical sequence.

Now a day for most commercial and general engineering applications programs (called software packages) are readily available.

These are applications where we still have to write programs, giving more scope for software programmers.

Computer Hardware and Software:

A computer(computer system) basically consists of electronic components that are supported by electrical devices and mechanical systems. All these electronic, electrical, and mechanical components used in a computer are called computer Hardware.

Computer hardware components are actuated and controlled with the help of computer programs called computer software.

Computer software is classified into two categories:

• Application Software
• System Software

Developments (Generation of Computers):

Computers became commercially available during the early 1950s and many significant technological developments have taken place thereafter.

First-generation computers:

• Vacuum tubes were used as the principal electronic components.
• The speed of computing was measured in milliseconds.
• Limited storage capacity
• Punched cards were used for input/output operation.

Second-generation computers:

• Transistors and diodes were the principal electronic component.
• The speed of computing was measured in microseconds.
• Increased storage capacity
• Magnetic tapes were used for input/output operation.
• Considerable reduction in heat generation.

Third-generation computers:

• Used of Integrated Circuits(IC)
• The speed of computing was measured in nanoseconds.
• Occupied less space.
• Input/output device like visual display unit(Monitor), line printer, Magnetic Tapes.

Fourth-generation computer:

• Used of microprocessor chip (the entire CPU on a single silicon chip).
• Speed of computing was measured in nanoseconds and picoseconds.
• Occupied less space.
• Commonly available as a personal computer(PC).
• Mini and microcomputers were developed from the microprocessor.

Fifth-generation Computer:

• Used super large scale integration (SLSI) chip.
• Performing millions of instructions.
• The speed of processing is high.
• Used of RISC(Reduced Instructions Set Computing ) for processing.
• Most expensive.

Organization of a computer:

• Input
• Output
• Control Unit
• Memory unit.
• Arithmetic and Logical Unit(ALU)

Types of Computers:

Based on the speed of operation, memory capacity, hardware facilities, and cost, computers are  classified as follows:

• Mainframe computers system works at a high speed and have higher storage capacity. These computers support large terminals to use a variety of software applications.
• Minicomputer is a medium-sized and powerful computer used to serve many users simultaneously.
• Microcomputers are the commonly used general-purpose computer. The latest microcomputers work at greater speed and they can be easily linked to minicomputers or mainframe computers.

Data storage in a computer:

Storage of data in a computer is always in form of Binary Digits (Bits)

•   4 bits=1 Nibble
•   8 bits=1 byte
•  1024 bytes=1KB(KiloByte)
•  1024 KB=1MB(MegaByte)
•  1024 MB=1GB( GigaByte)
•  1024 GB=1 TB(TeraByte)

Input Device Examples:

Keyboard: A keyboard is used to enter data into a computer system. The keyboard contains function keys, numeric keys and toggle keys( Caps lock, Num lock, Scroll key)

Mouse: A mouse is a picking device used to select a command by moving it in any direction on a flat surface. It has two or three-button to confirm the selection.

Storage Device Examples:

Floppy Disk: A floppy disk is used to store data permanently, having a memory capacity of 1.44 MB.

Hard Disk: Hard disk is a reliable and permanent storage disk. It has a set of metal disks coated with magnetic material and is mounted on a central spinal which makes 7200 rpm.

Compact Disk: Compact Disk (CD) is an optical disk used to store data permanently. It is the most reliable storage media available. The CD drive commonly available is read-only. Read/ Write CD drives are also available. The storage capacity of a CD is 700MB.

Output Device Examples:

Monitor: A monitor is a display device. The size of a commonly used color monitor is 15 inches.

Printer: The printer is used to print the result and text on a paper. Dot-matrix printer, inject printer and laser printer are commonly used.

Computer Memory (Primary & Secondary)  Types of Computer Memory

Definition of Computer Memory, what is computer memory: storage area of computer is called computer memory.

1.Primary Memory :  

Primary Memory is directly assembled by CPU, it may non volatile or volatile.

1.1 RAM (Random Access Memory, RAM is volatile memory)

• SRAM
• DRAM

1.2 ROM (Read-only Memory, ROM is non Volatile memory)

• PROM (Programmable ROM)
• EPROM (Electronic Programmable ROM)
• EEPROM(Electrically Erasable Programmable ROM)

2. Secondary Memory:

This type of memory can not directly assert by CPU, CPU can assert this memory through primary memory.

• Magnetic Tap
• Magnetic Disk(Hard Disk)
• Optical Disk(CD, DVD)
• Flash Drive