SS1 FIRST TERM 2023 WEEK EIGHT & NINE LESSON NOTE

 

Ss 1

TOPIC: Overview of the computer system  

Objective:

At the end of topic you should be able to:

1.Define a computer system

2. State the components of computer system

3. State the characteristics of a computer        

Introduction

Definition of Computer System

·       Computer system can be defined as an electronic device which manipulates data and produces output using step-by-step instructions.

·       A programmable machine that receives, stores, retrieves, processes and outputs data

·       A computer may be defined as a machine that can solve problems by accepting data, performing certain operations and presenting the results of those operations under the direction of detailed step by step instructions.

Constituents of a Computer

The two major constituents of the computer are hardware and software

1.    Hardware: Hardware can be defined as all the parts of the computer that are tangible. I.e. they are the parts of the computer you can see, touch, or handle.

Examples of Hardware

The following list represents a basic set of set of hardware found in most computers

a.  PC case, b. Motherboard, c. Hard Disk Drive (HDD), d. Floppy Disk Drive (FDD), e. Compact Disk Drive (CDD), f. Digital Video Disk Drive (DVD), g. Monitor, h. Keyboard, i. Power supply, j. Mouse, k. Cables and wires.

Hardware can be broadly divided into two parts namely: System unit and Peripherals.

System Unit: System unit is that part of the computer that houses electronic components of the computer used to process data.

Peripherals: A computer peripheral is any external device that provides input and output for the computer. The term peripherals refer to all hardware devices that are attached to the computer and are controlled by the computer system. Peripheral devices, are sometimes called "I/O devices"

Types of Peripheral Devices

There are many different peripheral devices, but they fall into three general categories:

Input devices, such as a mouse and a keyboard

Output devices, such as a monitor and a printer

Storage devices, such as a hard drive or flash drive

2.    Software: software is defined as set of instructions and procedures passed to the computer to perform certain activities or task. It can also be defined as a set of instructions that direct the activities of the computer system in order to undertake a specific task. Unlike the hardware, software cannot be seen or touched. 

Examples of Software

The following list represents some software found in most computers.

a. Windows, b. MS word, c. Norton anti-virus, d. CorelDraw, e. MS Access f. MS Excel, g. BASIC Language, h. Assembler, etc.

Computer software is divided into two broad groups, these are:

1.    System Software

2.    Application software 

System Software

System software is a collection of programs that supports computer operations. It can also be defined as programs that helps run the computer hardware and software. E.g. Operating System, Translators and Utility programs.

Application Software

These are software that allow humans (the users) to accomplish one or more specific (non-computer) task. E.g. Word processing software, Spreadsheet software, Presentation software, Database packages, Graphics packages, Etc.

Characteristics of Computer

The characteristics possessed by computer can be listed as follows

1.    Speed: A computer can add and subtract numbers, compare letters to find alphabetic sequence, move and copy numbers and letters. This feature is very important and useful for humans.

2.    Accuracy: Computers are very accurate. They can perform hundreds of thousands of operations with great accuracy as there are no moving parts to wear and go wrong. They can run without error for months at a time.

3.    Storage: Because various computer devices can store lots of data in a small area, there are tremendous saving in the storage area required to maintain the records necessary in a business.

4.    Versatility: A computer can perform many different types of tasks. You can perform arithmetic operations, do word processing, send email, and use Internet.

5.    Automation: Automation is one of the most important features of the computer. Once a command is given to the computer, it can perform the job without the need of human help until the job has been completed.

6.    Diligence: Computers do not get tired like humans. They can perform the jobs continuously for days and even weeks together without errors without affecting its speed and accuracy.

7.    Cost: Hardware costs have been decreasing at an estimated annual rate of 25 percent.

8.    Electronic in nature

9.    Interactive

Classification of Computer

1)     Classification According to Purpose

a.       General Purpose Computer- A general purpose computer is designed to perform a wide variety of tasks

b.      Specific Purpose Computer- These computers are designed to handle a single problem

2)     Classification According to Type of Data-handling Techniques

a.       Analog Computers: These are computer that represents data by measurable quantities, as voltages, rotation of gears, in order to solve problems.

b.      Digital Computer. A digital computer is a computer that performs calculations and logical operations with quantities represented as digits, usually in the binary number system.

c.       Hybrid Computer: A hybrid computer is a type of computer that offers the functionalities of both a digital and an analog computer

3)     Classification of Computer by Size/Speed

a.         Microcomputer: Microcomputers are relatively small and low-cost. They consist of a CPU, an input unit, an output unit, a storage unit, and the software

b.        Minicomputers: Minicomputers are digital computers, generally used in multi-user systems. They have high processing speed and high storage capacity than the microcomputers. Minicomputers can support up to 4 – 200 users simultaneously

c.         Mainframe: Mainframe computers are multi-user, multi-programming, and high-performance computers. They operate at a very high speed, have a very large storage capacity, and can handle the workload of many users.

d.        Supercomputer: Supercomputers are the fastest and most expensive machines. They have high processing speed compared to other computers. The speed of a supercomputer is generally measured in FLOPS (Floating Point Operations Per Second). Some of the faster supercomputers can perform trillions of calculations per second