ABC of Computers

PC (Desktop)          Laptop                   Server

What is a computer?
A computer is a tool that we can use to make our life easier the same way cars and airplanes have.
The actual definition of a computer is:

         A programmable electronic device that stores, retrieves, and processes data.

The real advantages of computers are the fact that they can do things faster than humans and can repeat the same thing millions of times without getting bored or tired.

The goal here is to make you familiar with computers and their jargons and not to make you an expert.
A computer is composed of:

         1. Hardware
         2. Software

The physical components of a computer, for example the keyboard, the monitor or the mouse are computer hardware. We usually say that if you get hit on the head with any part of the computer and it hurts, then it is a hardware part.

Software is a computer program; the set of all programs available to the computer.

Computer System
A computer system or system for short is both the hardware and the software combined.

Computer Programs
A computer program is a sequence of instructions outlining the steps to be performed by the computers. To understand what is a program we may need to understand the following analogy. If a person is going on a camping trip and has prepared a list of instructions or steps for what will be done on the trip. In other words, there is a program for what to do on this camping trip. The same thing applies for a computer program, which is steps or instructions for the computer to execute or do.

The CPU is the “brain” of the computer and it interprets and executes the program instructions. It is actually a computer chip that is located inside the computer and it runs the entire computer.

Like humans, computers need to memorize what to do. There are several types of computer memories, but we only need to know two, which are:

         1. Internal memory – main memory
         2. Secondary memory or storage – permanent memory.

The diagram above shows how the CPU reads instructions from main memory and executes them one after another. The main memory loads or retrieves programs or files from the hard drive or CD ROM. The hard drive and CD ROM store programs or files permanently. A computer program is loaded from the hard drive to main memory, where the CPU retrieves and executes the program instructions.

Internal Memory (RAM)
Computer memory is used to temporarily hold the instructions of an executing program. Memory can be thought of as a scratchpad for the computer to work with. It is volatile, which exits as long as the computer is running and power is on.

RAM = Random access memory, which you access any part of RAM at random without any restrictions.

Secondary Memory
It is the disk drive on a computer and it is permanent and can be saved as well as retrieved. The hard drive is a magnetic device and stores large amounts of data.

Hard Drive
It is a secondary mass storage medium providing a large amount of permanent storage. A rotating magnetic disk used to store and retrieve magnetically encoded data through read/write (head).

It is a form of read-only optical storage using a compact disk. Read-only means once the data is stored on it; the data cannot be changed or rewritten. It is also some sort of memory or storage. It is an optical device, which means it uses light to store data.

Memory Unit
It is the internal data storage for the computer.

A BInary digiT (0 or 1) often used to present information in computers.

A sequence of 8 bits used to encode a character within the computer.

An intermediate data storage area used to balance the different operating speeds of computer components. Example: The speed of any I/O (printer) and CPU

What is PC?
PC = Personal Computer; a small, one-user computer that is relatively inexpensive to own.

A portable computer designed to fit one’s lap or some other nonpermanent surface where no AC power is available.

It is an electronic device that transfers a page of document or a picture into a digital or a computer image.

It is a communication device that allows computers to communicate using phone lines.

A computer video screen.   Also see the sction on resolution.

Machine Language
The language used directly by the computer and is composed of ones and zeros. It is a language that the computer understands.

It is all or part of a program or to write all or part of a program in programming language.

It is a program that translates a high level language (C++ Source code) into machine language.

It is to use a compiler to translate a program in high-level language into machine language.

A program that translates each statement of a high-level language source program into sequence of code instructions, which are executed before the next statement of the source program is translated.

Execute a Program (Run a Program)
To carry out the instruction(s) in a statement or a program; to run a program

An error in a program that prevents compilation or execution or causes incorrect results

Operating system
An operating system is a program, which acts as an interface between a user of a computer and the computer hardware. There are several operating systems, which computers use; for example Windows, DOS or Unix. The purpose of an operating system is to provide an environment in which a user may execute programs. The primary goal of an operating system is thus to make the computer system convenient to use. A secondary goal is to use the computer hardware in an efficient manner. For example, all you need to do to print a file is to ask the operating system (Windows) to do to the printing for you. Otherwise if you want to print a file, you may have to do a number of tasks such as the following:

         1. Get the printer ready
         2. Set the correct fonts
         3. Send the data
         4. Check the status of the printer

Well, if it was not for the operating system, you may have to do all the above steps and more. Therefore, operating systems make life easier for the users.

In order for us to store data or programs, we use files as a means of storage place. Basically a file is a collection or an album to store data. A file is a collection of related data, which is usually stored on disk or tape. There are different types of files and the following are some of the most common:

         1. Text files
         2. Executable programs – known as applications
         3. Images
         4. Sound
         5. Compressed files

Text File
A file of text or a file that is composed of ASCII numbers or characters

File Functions
Files functions can be used in ways including the following:

         1. Save – to store on the hard drive permanently
         2. Retrieve – to retrieve from hard drive
         3. Edit – to be able to change the content of the file
         4. Run – only application (programs) can run or be executed

Directory – Folder
Files can be grouped together under a directory or a folder. A directory or a folder is a group of files stored together for the purpose of organization. For example, on any given computer system there may exist over 30,000 files and if there were no folders to group and organize these files, it would be impossible to lookup or use a file.

Computer users must create folders and put their files in them otherwise it would be very difficult to find any of their files. For example, you can create a folder and name it “MySchoolInformation” and put all the school files into that folder.

An interaction program that allows the user to create and alter text files such as data.

Function Keys
On the top part of any keyboard, there are 12 keys with range of the following:

         F1   F2   …   F12

These keys are known as functions keys. Depending on the application running, they have special functions. They are more of a short cut for computer functions or tasks. For example, pressing the “F2” function key on Microsoft Word will save the document you are editing or working with.


A network is a collection of computers, terminals and other equipments that uses communication channels (such as phone lines, microwaves or satellites) to share data, information, hardware and software.

A network is composed of one (or more) central computer and these computers are called servers. Basically, a server is a computer that is available for many users to use and it may be located at a remote place such as a different building, state or country. The server may have a number of resources that an outside computer (user or client) can access. It does all the administrating of its resources. It keeps an account database of all it users.

Remote Access
Server hardware is a computer that has an operating system, application programs, utilities, users (clients), protocols and security. Think of a server as an operating system’s services on a remote machine. A remote access is the ability to use server and their services.

Web Server (HTTP Server)
A Web server is an HTTP server, which uses an HTTP (Hypertext Transfer Protocol) protocol. An HTTP is a Stateless and a connectionless protocol. HTTP protocol is a generic application protocol that allows independent system to transfer data. HTTP communication takes place over TCP/IP connection. The default port of an HTTP server is 80. An HTTP is a request/response-oriented protocol.

The process of transferring and saving software or data from a PC to a server or another computer

The process of transferring and saving software or data from a server or another computer to a PC

It is a process, which a person has to perform to use a computer that is restricted to a number of users.

Login name or ID
It is name used as an ID for a person to access or logon into a computer.

A secret combination of letters, number and/or symbols that is used to ensure that only the legitimate user can access a computer with the given user login name or ID

The Client/Server concept needs some clarification. A client is the receiver of a service and server is the service provider. For example, a computer requesting data from a network is the client and the computer that is providing the data is the server. Does this means a client and server can be toggled? The answer is yes, but there is a dedicated server with only one job, which is to provide service to clients. The same holds true for some clients, they have nothing to offer but request. On any network, there is a layer of software that acts as a server for that network. The client can use this layer of software by using specific commands.

World Wide Web
The Internet or the Web is hundreds of thousands of networks (servers) that are connected to each other like a spider web. Looking at a spider web and how the spider weaves a large net of silk, the spider web is an equal analogy of the Internet. The term World Wide Web (or the Web for short) may have come from the spider web analogy.

Each of the networks is an independent network with its own operating system and applications, data and hardware.

A Web user (client)
A Web user or Web client can connect and use any of the sites (servers) on the Web, the Web client or user can access the entire Web services and hardware (if permissible) as if they are local to the client network and services. The Web gives the client a worldwide access to services and information.

Web service providers
Web service providers are companies that provide Web access at a cost. Service providers provide their users with a local phone call service. The cost of using such services is very small compared to actual cost if the user tries to do the same thing on his/her own.

A Web page is a text file with HTML tags (commands) to be interpreted by an interpreter. A Web Browser is a program (interpreter), which is used to execute the Web pages. The two most well known Web Browsers are Netscape Navigator and Microsoft Internet Explorer, which are used by the vast majority. A Web Browser sometimes called a “user agent”, which is located on the user machine. It works by using a special protocol called HTTP to request especially encoded text document from a Web server. The text document contains special instructions (written in HTML) that tell the Browser how to display the document on the user’s screen.

The HTML is a computer language designed for a Web browser to execute. It is not like C, C++ or Java programming languages, but it is an interpreted or a script language.

Web Page
A Web page is a text file containing a number of commands to be executed by a program called “Web Browser”. It is basically a script to be executed by an interpreter. The Web page commands are HTML commands, which are known as HTML tags. These commands are used to create a Web page with messages, banners, logos, buttons, graphic images, as well as calling Java applets, or run programs (CGI).

Web Search Engine
A search engine is a Web service that helps Web users find information about any topic. For example, a Web user can search for “travel” and a search engine such as Yahoo can provide a listing of Web pages and websites on travel. Search engines basically work using the following three steps:

         1. To visit Web sites and read every Web page information and categorize this information.
         2. To index these Web pages to speed the search
         3. Users search the search engine listing to find a match of what they are seeking.

Screen, Pixels and Resolution
A computer screen is the television-like device on which the output of the computer is shown. A computer screen is composed of a number of pixels. A pixel is a dot of light on the screen. The number of pixels on the screen defines the quality of the picture. The higher the number of pixels, the superior quality the display would be. This is known as screen resolution, which is the number of horizontal and vertical pixels on a screen.


The screen is designed to use these pixels to display text and images. The above images show how the computer lights the pixels, which displays the text and images. The greater the number of pixels the sharper the display would be.

Screen Setting
You can customize your screen to a number of different settings. The following are the steps for Windows setting:

         1. Click the “Start” button and point to the “Settings”
         2. Click on “Control Panel” and the Control Panel Window appears.
         3. Double click on the “Display” and the “Display Properties” dialog box appears.
         4. Click on the “Setting” tap and the “Colors” and “Screen Area” display appears.
         5. Use the “Screen Area” dial for more or less resolution.
         6. We recommend that the “Screen Area” should be “1024 by 786 (or 800)” or more.
             This would increase the screen resolution and provide a better display.
         7. Click on the “Apply” button and click the following “OK” buttons to set your screen.