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ITC Unit 1 Introduction to Computer Systems

A computer is a device that accepts information (in the form of digitalized data) and

manipulates it for some result based on a program or sequence of instructions on how the data

is to be processed.

Hardware refers to any and all parts on, connected to, or about the computer that you can

actually physically touch. Parts like the computer case, the mouse, the monitor (display screen),the keyboard and speakers are all a good definition of computer hardware. Other examples are:

keyboard, RAM, Router, processor, sensors, network cards, loudspeaker, ports, hubs, etc.

Computer software is the set of instructions that the computer carries out, usually one after

another and is stored in Primary Memory when executed.

Data is a collection of facts, such as values or measurements. It can be numbers, words,

measurements, observations or even just descriptions of things.

To a computer a data is a collection of Bits (Binary Digits) i.e., 0s and 1s.

A bit (short for binary digit ) is the smallest unit of data in a computer. A bit has a single binaryvalue, either 0 or 1. It can be easily represented in a computer by switches or transistors, either

on or off. A collection of bits can represent any data.

A system is a collection of elements or components that are organized for a common purpose.

It has a boundary. Examples of system are: Digestive system, Banking System, etc.

A computer system is a collection of hardware, software and data needed to solve a real world

problem. The component of computer system depends on the problem being solved.

Computer hardware is classified into: input and output devices.

An input device is any peripheral (piece of computer hardware equipment) used to providedata and control signals to a computer. It changes analogue data into digital data. Some

examples of input devices are: keyboard, Mouse, webcam, microphone, scanner, etc.

Some more complex input devices are:

a) Gamepad (or joy

pad)

b) Paddle (game

controller)

c) Wii Remote

d) Fingerprint scanner

e) Barcode reader

f) 3D scanner

g) Laser rangefinder

An output device is any piece of computer hardware equipment used to communicate the

results of data processing carried out by an information processing system (such as a

computer) to the outside world. It converts digital data to analogue information.

Some of the common output devices are: printer, monitors, and speakers.

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ITC Unit 1 Introduction to Computer Systems

More examples of output devices are:

a) plotters

b) motors

c) heaters

d) lights

e) actuators

f) switches

 

Analogue and digital data:

Analogue data: Data represented by a physical quantity that is considered to be continuously

variable and has a magnitude directly proportional to the data or to a suitable function of the

data.

Digital data: Consists of discrete, discontinuous binary digits.

A storage device is a hardware device capable of storing information for future use. There are

two storage devices used in computers; a primary storage device such as computer RAM and asecondary storage device such as a computer hard disk drive.

RAM is volatile and limited.

Primary storage is a storage location that holds memory for short periods of times while the

computer is on. Example RAM and Cache.

Secondary storage is a storage medium that holds information until it is deleted or overwritten

regardless if the computer has power. It is getting faster and cheaper all the time. Examples:

Magnetic: Hard Disks, Tapes

Optical: CD, DVD, Blu Ray, etc.

Solid State: Flash Memory, SIM Cards, USB Memory Sticks

Software is a collection of instructions that enables a user to interact with the computer or have

the computer perform specific tasks for them. It is produced as a program, stored in secondary

storage and copied into RAM for running.

It can be divided into two main groups:

System software is a program that manages and supports the computer resources and

operations of a computer system while it executes various tasks such as processing data andinformation, controlling hardware components, and allowing users to use application software.

That is, systems software functions as a bridge between computer system hardware and the

application software.

Application software is computer software designed to help the user to perform singular or

multiple related specific tasks. It helps us to solve real world problems.

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ITC Unit 1 Introduction to Computer Systems

System software comprises of:

a) Operating systems

b) Translation

software

c) Database

management

systems

d) Utilities

An operating system is software, consisting of programs and data, which runs on computers,

manages computer hardware resources, and provides common services for execution of

various application software. It also hides the complexities of the machine, manages memory,

peripherals and files. Examples: Windows OS, MAC OS, Linux, UNIX, etc.

Types of operating systems are:

a) Single job stream

b) Multiprogramming

c) Real-time

d) Network

Single job stream: Processes one job after another, the OS has to load and run each job.

Multiprogramming: In this type of OS several applications maybe simultaneously loaded and

used in the memory. Each process is allocated a time slice. While the processor handles only

one application at a particular time it is capable of switching between the applications effectively

to apparently simultaneously execute each application. This type of operating system is seen

everywhere today and is the most common type of OS, the Windows operating system would be

an example.

Real-time: A real-time operating system processes inputs simultaneously, fast enough to affect

the next input or process. Real-time systems are usually used to control complex systems that

require a lot of processing like machinery and industrial systems.

Network: Network OS is the software that runs on a server and enables the server to manage

data, users, groups, security, applications, and other networking functions. It helps to

communicate, share resources and divide work among networked computers.

Translation software: It translates source code into machine code.

Assembler - works on low level source code  – produces a runnable program file

Compiler - works on high level source code  – produces a runnable program file

Interpreter - works on high level code and executes it as it goes  – no new file produced

A Database Management System (DBMS) is a software package with computer programs that

controls the creation, maintenance, and the use of a database.

o It separates data from applications

o Allow applications to be created that do not conflict with each other.

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ITC Unit 1 Introduction to Computer Systems

Utilities are small programs designed to do a limited range of tasks. Examples: formatter,

defragmenter, text editor, compression software, etc.

Different types of computer system are:

o Personal Computer

o Desktop

o Laptop

o PDA

o Notebook

o Sub-notebook

o Workstation

o Server

o Mainframe

o Minicomputer

o Supercomputer

o Embedded Devices

  Data is raw material for data processing. Data relates to fact, event and transactions.

  Information is data that has been processed in such a way as to be meaningful to the

person who receives it. It is anything that is communicated.

231189 is data; 21/11/89 is information as it looks like a date.

Computer History

First Generation

Example: Colossus

o The first electronic, programmable, digital computing device

o Used 2400 electronic valves

o Designed by Tommy Flowers

o Used to decode wartime code messages

Second Generation

o Transistors Replace Valves:

o Faster

o Use less energy

o More reliable

o Cheaper

o Smaller

Third Generation

o Integrated circuits

o More size and cost reductions

o Faster

Fourth Generation

o Millions of transistors packed onto a

chip

o More size reduction

o More speed gains

In CUI one task runs at a time.Everything done by commands.Application: MS Dos

GUI stands for Graphical User interface.In GUI more tasks can run simultaneously.Work done by pointing devices like mouseVery user friendlyApplication: Window