Images of EGYPT

Egypt at the beginning of the 20th century

Information Networks

A LAN

(Local Area Network) is a system where individual PCs are connected together within a company or organization. For instance if ten people are working together within an office to connect them to have a single printer and all ten people can print to it In a similar way, other devices such as modems or scanners can Even more useful is the ability to share information when connected to a network

A WAN

(Wide Area Network) allows you to connect to other computers over a wider area (i.e. the whole world)

Client/server

This term mean to the type of network where resources are kept centrally on the server and used locally by the client. The server tends to be a very powerful PC (or group of PCs), while each client workstation, which the users have, is less powerful

Workgroup

Groups of people working together can share their resources with each other. People within the workgroup can share information on their hard disks as well as sharing printers, modems and scanners. The workgroup is connected via a computer network. This network can simply consist of a few computers at a single location physically connected to each other via a network cable, or it may be a workgroup of computers connected globally via the Internet. The networked nature of computers means that the physical distance between workgroups members is fast becoming irrelevant

Intranet and Extranet

An Intranet

It is a smaller, closed version of the Internet, which can only be accessed by authorized members of an organization. Intranets are becoming an increasingly popular way to share information within a company or other organization. An Intranet uses Internet technologies to allow users to access company documents, search databases, schedule meetings and of course send emails. Once a company has installed a comprehensive Intranet many users need only one piece of software on their PC, a web browser

An Extranet

is an Intranet which is partially accessible to authorized outsiders. An Intranet is normally only accessible by members of the same company or organization; an extranet also allows outsiders who have been issued with a password to gain limited access to information held on a company network. Extranets are being used as a way for business partners to share information.

The Internet

A collection of networks started by and for the US military to enable them to 'survive' a nuclear war. Later adopted by the educational system, and now exploited by the commercial world The Internet is a global network of interconnected networks The unique thing about the Internet is the sheer amount of information which you can access from it the Internet enables all of the following to take place:

Sharing information on Web sites

Moving files between computers at different locations

Sending email to recipients around the world

Holding private video and audio conferences

Working collaboratively with people at other locations

The difference between the World Wide Web (WWW) and the Internet

The World Wide Web (WWW) is just a small part of the Internet as a whole. The Internet relates to all the hardware and software involved, as well as the WWW, it also includes FTP (File Transfer Protocol), email and newsgroups. The WWW is basically the text and pictures which you can view using your web browser, such as Microsoft Internet Explorer, or Netscape Navigator

The Telephone Network in Computing

If you use a modem to connect to the Internet, then this connection is made by the telephone network.

PSTN

(Or Public Switched Telephone Network) is the technical name for the public telephone system It is based on traditional 'copper wire' technology and can transmit analogue voice data

PSDN

(Or Public Switched Data Network) is simply the technical name for the telephone system in use today

ISDN

Stands for "Integrated Services Digital Network" ISDN dates back to 1984, and allow much faster transfer rates than when using modems. Using ISDN, you can transfer 64 Kbit or 128 Kbit of data per second

ADSL

Short for 'Asymmetric Digital Subscriber Line' A more recent technology which allows more data to be sent over existing copper telephone lines, but requires a special ADSL modem ADSL allows data transfer rates of ranging from to 8 Mbps when receiving data (called the downstream rate) and from 16 to 640 Kbps when sending data (called the upstream rate)

DSL

Refers collectively to all types of 'Digital Subscriber Lines', the two main categories being ADSL and SDSLDSL technology allows faster data transfer while still using copper wires (as opposed to optic fiber cables)

Modem

Modem stands for "MODulate/DEModulate". The modem sends information from your computer across the telephone system. The modem at the other end of the phone line, converts the signal back into a format which can be used by the receiving computer

Digital modem and analogue modem

A digital system uses 1 or 0 to transmit data or to represent data. Thus, a digital clock will display whole seconds, whole minutes and whole hours. An analogue system, such as a traditional clock, does not use multiples of 1 or 0, but rather uses the full range of numbers, including fractions. In this way, an analogue clock can display fractions of a second

Baud rate

The baud rate tells you how fast a modem can send/receive data. Most modern modems have a maximum baud rate of 56 Kilobits per second (Kb/sec)

Software

The operating system

is a special type of program which loads automatically when you start your computer. The operating system allows you to use the advanced features of a modern computer without having to learn all the details of how the hardware works. There are a number of different types of operating system in common use. The IBM PC (Personal Computer) was introduced way back in 1981 and was originally supplied with an operating system called DOS (Disk Operating System). This operating system was very basic, and you had to be a bit of a computer expert just to understand how to use it. It was NOT user-friendly. Later on, Microsoft introduced Windows and this is the operating system which is most widely used on PCs today.

• To complicate matters further, there are a number of different types of Windows. The first widely used version of Windows was called Windows 3.1. This was more powerful than DOS and far easier to use. It had a Graphical User Interface (GUI), i.e. you could 'drive' it using a mouse and drop down menus. Later, different releases of Windows were introduced. The good news is that later versions of Microsoft Windows look almost identical to each other and are all much easier to use than Windows 3.1.

• IBM produced an operating system called OS/2 but this was largely ignored and is only used by a few companies.

• UNIX and Linux are other examples of operating systems which may be run on PCs.

• Other types of computers, such as those manufactured by Apple have a completely different operating system.

A Graphical User Interface (GUI)

It is simply an additional part of the operating system which displays windows and drop down menus, and also enables you to drive your computer using a mouse. Examples of operating system which use a GUI include Windows the original version of DOS there are no menus, no icons and nothing for the mouse to click on. You had to know a special language which you then typed into the computer to make it do anything The advantages of using a GUI (Graphical User Interface)

• All programs look similar and when you switch from a program supplied by one manufacturer to a different program supplied by another manufacturer, you will find the transition very easy.

• Application programs work in the same way as the underlying operating system, and also look very similar, which means that they are easier to learn and use.

• The GUI also allows programmers to easily write consistent looking programs

An application program is the type of program which you use once the operating system has been loaded into memory (RAM). Examples include word processing programs (for producing letters, memos etc), spreadsheets (for doing accounts and working with numbers), databases (for organising large amounts of information), games and graphics programs (for producing pictures, advertisements, manuals etc)

Systems development

The way new software is specified, written by programmers, tested and then delivered to the user

Systems development cycle

• Most IT projects work in cycles. First, the needs of the computer users must be analyzed. This task is often performed by a professional called a 'Systems Analysts' who will ask the users exactly what they would like the system to do, and then draw up plans on how this can be implemented on a real, computer based, system.

• The programmer will take the specifications from the Systems Analyst and then convert the broad brushstrokes into actual computer programs. Ideally at this point there should be testing and input from the users so that what is produced by the programmers is actually what they asked for.

• Finally, there is the implementation process, during which all users are introduced to the new systems, which often involves an element of training.

• Once the users start using the new system, they will often suggest new improvements and the whole process are started all over again. These are methodologies for defining a systems development cycle and often you will see four key stages, as detailed below.

- Analysis

- Design

- Programming

- Testing

Hardware

Central Processing Unit

The CPU is the brains within your computer. It performs most of the calculations within the computer and is responsible for the smooth running of your operating system (Microsoft Windows) as well as your application programs, such as word-processors, spreadsheets and databases. There is a small amount of memory associated with the CPU, which it uses to perform these operations. It also accesses and uses the main memory (RAM - Random Access Memory) within your computer. In many ways, the CPU is the single most important item within your computer which governs the overall speed of your computer. The CPU's speed is measured in MHz of GHz. This relates to the frequency at which the CPU runs and the higher the MHz (or GHz) rating of your CPU the faster your computer will run. To give you some indication of how PCs have advanced over the years, the original IBM PC released in 1981 ran at less than 5 MHz while modern PCs can run at speeds well in excess of 2000 MHz (2 GHz). Note that 1000 MHz is the same a 1 GHz

Memory

You can store data on your hard disk, while data which is being processed is stored in RAM (Random Access Memory). Data which is stored on a hard disk can be permanent, while data in RAM is only temporary. Normally when people talk about memory in relation to a PC, they are talking about RAM

RAM

Random Access Memory (RAM) is the main 'working' memory used by the computer. When the operating system loads from disk when you first switch on the computer, it is copied into RAM Microsoft Windows based computer will operate faster if you install more RAM Data and programs stored in RAM are volatile (i.e. the information is lost when you switch off the computer)

What is ROM

Read Only Memory (ROM) as the name suggests is a special type of memory chip which holds software which can be read but not written to. A good example is the ROM-BIOS chip, which contains read-only software. Often network cards and video cards also contain ROM chips

ROM-BIOS

The 'Read Only Memory Basic Input Output System' chip is a chip located on the computer's system (mother) board, which contains software. This software performs a variety of tasks. When you first switch on the computer the ROM-BIOS software performs a self-diagnostic to check that the computer is working OK. This software then loads your operating system from the disk into the RAM

Flash BIOS

Most modern computers are actually supplied with flash BIOS rather than ROM-BIOS. This chip contains exactly the same type of in-built software, but has the advantage that the software on the chip can be upgraded. This upgrade is achieved by simply running a small program supplied by the computer manufacturer

Video (graphics) memory

The picture which you see on your screen is a form of data and this data has to be stored somewhere. The on-screen pictures are held in special memory chips called video memory chips; these chips are usually located on the video card. A modern computer will be supplied with several Megabytes of video memory

How computer memory is measured

The simplest unit of memory is the bit. A single bit is equal to either a numerical 1 or 0 at any given time. Each bit of memory is like a tiny switch that the computer can turn on or off: on equals 1 and off equals 0. This system is called the binary system of counting.

Modern computers contain many bits of memory, referred to in increasingly large units:

A byte is 8 bits.

A kilobyte (KB) is 1,024 bytes. Computers use binary arithmetic, which makes 1,024 a "round" number in computing terms.

A megabyte (MB) is 1,024KB, or roughly 1 million bytes.

A gigabyte (GB) is 1,024MB, or roughly 1 billion bytes.

A terabyte (TB) is 1,024GB, or roughly 1 trillion bytes.

A byte will hold a single character of the alphabet; each letter is represented by a particular code of 1s and 0s. (For example, the letter "A" is usually stored as 01000001 in "computer language.")

A page of text will take about 5KB to store.

This entire book takes up about 5MB of RAM.

A GB of text would come to about 2,000 books, a good-sized personal library.

The Library of Congress holds nearly 25 million books. That's about 12.5TB of text.

Of course, not all the information stored on your computer is in the form of text. Programs, graphics, sounds, movies, drawings, and other forms of information all take up RAM when they're current in your computer. A typical application might occupy anywhere from 100KB to 100MB of RAM while it's running

Input Devices

The mouse came into common use on a PC with the introduction of the Microsoft Windows operating system. Before this, the operating system (DOS) would normally be controlled via the keyboard. These days it is vital to be a competent mouse user. There are many different types of mice, a commonly used model now has a small wheel on it which when combined with the correct software allows additional functionality and fine control over the use of your applications

The keyboard is still the commonest way of entering information into a computer. There are a number of different types, including those specially designed for use with Microsoft Windows. The quality of the keyboard is often overlooked when buying a PC; it should be robust and easy to use

A tracker ball is an alternative to the traditional mouse and favored by graphic designers. Tracker balls often give much finer control over the movement of the items on the screen. They may take a while to get used to if you are used to the traditional mouse, but offer a lot in terms of added flexibility

A scanner allows you to scan printed material and convert it into a file format which may be used within the PC. You can scan pictures and then manipulate these inside the PC using a graphics application of your choice. In addition, you can scan printed text and convert this not just to a picture of the text but also to, actual text which can be manipulated and edited as text within your word-processor. There are a number of specialist programs, generically called OCR (Optical Character Recognition) programs which are specifically designed for converting printed text into editable text within your applications

A touch pad is a desktop device and responds to pressure. Used in conjunction with a special pen they can be used by graphic artists wishing to create original, digital artwork

A light pen is used to allow users to point to areas on a screen and is often used to select menu choices

Joysticks many games require a joystick for the proper playing of the game. There are many different types

Voice input for PCs (microphones) Early voice recognition systems offered very poor results, due to the limitations of the software combined with hardware limitations. It takes an awful lot of CPU processing power to convert the spoken word into text which appears on the screen. Things are changing rapidly however and recent systems allow you to talk to a PC and see text appear on the screen. Most of these systems require an initial training period, where you train the software to respond to your particular voice. Whilst still not perfect this is a key technology of the future

Web Cams You can now use a small digital movie camera (a Web cam) mounted on the PC monitor to allow two-way communication involving not just text communication but sound and video communication as well

A digital camera can be used in the same way a traditional camera can, but instead of storing images on rolls of film which require developing, the images are stored digitally in memory housed within the camera. These pictures can easily be transferred to your computer and then manipulated within any graphics programs which you have installed on your computer. Currently they are limited by the quality of the image recorded and the number of pictures which you may store within the camera

Output Devices

The VDU (Visual Display Unit) is the computer screen used for outputting information in an understandable format for humans. Remember that at the end of the day the computer works in binary code (a series of on/off impulses). It is hard to realize that the original electronic computers did not have a screen

Flat screen monitors Traditional computer monitors are based on the same sort of technology which is used within a television screen. More recently, flat screen computer monitors have become available. These take up a lot less room on a desk and use less energy than the traditional, more bulky monitors

Computer presentation projection devices These are projection devices which can be attached to your computer and are useful for displaying presentations to a group of people. They are best used in combination with presentation programs, such as Microsoft PowerPoint. They are used within education and are also very popular for sales presentations. The price of these devices has dropped dramatically recently. When purchasing one of these devices the two things to look out for are the resolution (go for a minimum of XGA) and the brightness of the lamp (the brighter the better). Other factors to be aware of are the quietness (or otherwise) of the device, as well as the cost of replacement bulbs

Laser printers produce high print quality at high speed. They are called "laser printers" due to the fact that they contain a small laser within them. There is a wide range of laser printer manufacturers

Color laser printers originally, most laser printers would only print in black and white (mono). More recently color laser printers have dropped in price and are entering wide spread use. While many of these produce excellent results, you should be aware of the fact that the "price per page", especially if you are using a lot of color on a page can be very high compared to the cost of printing in black and white

Inkjet printers work by using tiny jets to spray ink onto the paper. Inkjet printers are very quiet in operation and produce print quality comparable to that of laser printers, though laser printers still have the edge in terms of speed. Inkjet printers are ideal for low volume printing where high quality print is required and speed is not a high priority, e.g. printing letters in a small office or in the home

Dot matrix printers work by firing a row of pins through an ink ribbon onto the paper. The more pins the print head has the higher the quality of the print, most modern dot matrix printers have 24 pins. Unfortunately, dot matrix printers can generate a lot of noise and do not produce a very high quality of print, especially when printing graphics. As a result, the inkjet printer has now largely replaced the dot matrix printer. Dot matrix printers are used for high volume / low quality printing, e.g. printing company pay slips

A plotter is an output device similar to a printer, but normally allows you to print larger images. Their use is common in the design and research sector

Speakers Most computers are sold with the capability to add a pair of speakers to your system unit. In fact, in some cases, the monitor may have speakers built directly into the unit. This enhances the value of educational and presentation products and can now be considered a standard PC component

Input/output Devices

Some devices are both input and output devices. A modem can be used for downloading information from web sites and receiving emails. It can also be used for uploading and sending emails. A touch screen can display a menu system (output device), and accept input when people touch the menus displayed on the screen

Computer Performance

The factors which impact on a computer's performance

CPU Clock speed

The computer clock speed governs how fast the CPU will run. The higher the clock speed the faster the computer will work for you. The clock speed is given in megahertz (MHz) The higher the MHz speed the faster the computer

RAM size

As a rule the more memory you have the faster the PC will appear to operate. Windows also uses the hard disk a lot, so logically the faster the hard disk can operate then again the faster the PC will appear to run

Hard disk speed and storage

Hard disks are also measured by their speed, defined by the disk access time, which is measured in milliseconds. The smaller this access time the faster the hard disk will store or retrieve data. The data storage capacity of hard disks continues to increase as new products are released. The disk storage capacity is measured in Gigabytes (GBytes). 1 GByte is equivalent to 1024 Mbytes

Free Hard Disk Space

To get the most out of your Windows based PC, you not only need a fast hard disk but also a large hard disk with plenty of "spare space". This is due to the fact Windows is constantly moving data between the hard disk and RAM (Random Access Memory). Microsoft Windows will create many so-called "temporary files" which it uses for managing your programs. In fact, if you have very little free hard disk space you may find that Microsoft Windows will not be able to run your programs at all

De-fragmenting Files

If you are running Windows you may find that if you click on the Start menu, select Programs, and then select the Accessories / System tools group, there is a de-fragmentation program. Running this periodically may noticeably speed up the operation of your PC. When you use a PC, over a period of time the files get broken up into separate pieces which are spread all over the hard disk. De-fragmentation means taking all the broken up pieces and joining them back together again

Multitasking considerations

Windows is a multitasking system, which means that it can run more than one program at a time. However the more programs which are running at the same time, the slower each one will run. To some extent this slowing effect depends on what each program is doing. Editing a large, full colour picture for instance can take up a lot of CPU time

Main Parts of a Personal Computer

The System Unit

It is the main PC box which houses the most elements which go together to make up the PC. For instance within the system unit is the computer system's motherboard, which contains all the main components, such as the CPU The system unit also houses items such as the hard disk, the floppy disk and CD-ROM drives etc

The System (Mother) Board

It is contained within your system unit and all the vital computer systems plug directly into the system board. The CPU is normally housed on your system board along with all the other electronic components. Other items such as the hard disk are attached to the system board, either directly or via cables. These boards are getting smaller and smaller as the components become more integrated

The CPU (Central Processing Unit)

It is normally an Intel Pentium and it is one of the most important components within your computer. It determines how fast your computer will run and is measured by its MHz or GHz speed. Thus, a 2 GHz Pentium is much faster than say a 1 GHz Pentium CPU. It is the CPU which performs all the calculations within the computer, when running programs such as word-processors, spreadsheets and databases.

Memory (RAM)

(Random Access Memory) within your computer is where the operating system is loaded to when you switch on your computer and also where your applications are copied to when you start an application the more RAM you have installed in your computer the better

ROM-BIOS

Read Only Memory - Basic Input Output System) chip is a special chip held on your computer's system (mother) board. It contains software which is required to make your computer work with your operating system it is responsible for copying your operating system into RAM when you switch on your computer

Serial Port

It is a socket located at the back of your computer which enables you to connect items to the computer, such as a modem. They are commonly labelled as COM1 or COM2

Parallel Port

It is a socket located at the back of your computer which enables you to connect items to the computer, such as a printer. It is commonly labelled as LPT1 or LPT2

Universal Serial Bus (USB)

It is a relatively new item within the PC. You will see one or more USB sockets at the back of the system unit, allowing you to plug in devices designed for the USB. These devices include printers, scanners and digital cameras

Input devices

It is allow you to input information to the computer and include things such as the keyboard and mouse

Output devices

It is allow you to output information from the computer and include the printer and the monitor

Peripheral device

It is any device which you can attach to your computer. Thus, you could attach a scanner or modem

The Keyboard

An Input device the keyboard allows you to type information into the computer

CD

Most computers are now supplied with a CD-ROM (Compact Disc - Read Only Memory) drive the benefit of a CD-ROM is that it can hold a vast amount of data (equivalent to the storage capacity of over 450 floppy disks) A CD-ROM can store 650 MB of data

DVD Drives

"Digital Versatile Disk" Similar to CD-ROM drives but allows you to use DVD disks, which contain vastly more information than a traditional CD-ROM disk. These also transfer the data from the disk to the computer far faster, allowing you to watch movies on your computer screen. A CD-ROM can store 650 MB of data, while a single-layer; single-sided DVD can store GB of data. The two-layer DVD standard allows a capacity of GB. A double-sided DVD increases the storage capacity to 17 GB (or over 25 times the data storage capacity of a CD-ROM)

Floppy disk

Also known as diskettes and hold relatively small amounts of data (1.44 Mbytes) Sometimes people will backup important data from their hard disk to floppy disks. However, as diskettes are notoriously unreliable this is not the best way of backing up important data

Zip Disc

A Zip disk is like a bigger version of the floppy disk, the main difference being that a single Zip disk can hold up to 250 Mbytes of data. They also offer increased speed compared to the old floppy disk

Hard (Fixed) Disk

Hard disks are the main, large data storage area within your computer. Hard disks are used to store your operating system, your application programs and your data. They are much faster than CD-ROMs and floppy disks and can also hold much more data. The picture shows the inside of a hard disk (which you would not normally see). Hard disks are installed within the system unit of your computer.

The Monitor

An output device the monitor is the TV type screen on which you view your programs. They are supplied in different sizes, common sizes range from 15" to 21" screens. You should be aware that poor quality or badly maintained monitors could harm your eyesight

Sound cards and speakers

Many computers are now supplied with sound cards and speakers which mean that when you run 'multi-media' programs, you can listen to sounds which are played back via your computer. If you have a microphone and suitable software, you can also record sounds. You can even purchase special software which will allow you to talk to your computer and get the computer to type the words you have spoken on your screen. In time, this type of software may replace the keyboard

Modems

A modem is a device which is used to attach your computer to the telephone system. The modem converts data into sound which is sent over the telephone line, the receiving modem turns the sounds back into data. If you wish to connect to the Internet, you will need a modem (or equivalent device). Modems used to be large boxes that you had to plug into the computer, but now modems boxes have become very small and in many cases the modem is actually inside the computer. If you are using ISDN or broadband then you will use another device similar to a modem

Printers

It is a device suitable to produce printed output on paper. There are a wide variety of printers; they differ in their speed, the size of the paper they can print on, and the process that they use for printing

Scanners

Allow you to scan printed materials into your computer, which can then be stored within the computer. These pictures can then be altered, resized and printed as required

Recordable CDs

CD-ROMs are read-only devices, but increasingly people are purchasing a special type of CD drive unit which allows you to record data, music or video to your own CDs. These devices require the purchase of special CDs to which you can write, called CD-R (Compact Disc – Recordable)

Tape backup

A tape backup unit allows for regular backing up of your data. These tapes can store a vast amount of data at a low cost. DAT (Digital Audio Tape) devices are commonly used for backups. The DAT tapes which are used can backup enormous amounts of data (i.e. over 4 Bytes per tape). The devices are also fast and reliable

External hard drives

Magnetic storage devices that is capable of storing large amounts of data there are hard drives that can connect to the computer outside the computer housing

ICDL Module 1 Concepts of Information Technology IT

Hardware, Software and Information Technology

Hardware

The term hardware refers to the physical components of your computer such as the system unit, mouse, keyboard, monitor etc

Software
The software is the collection of instructions which makes the computer work. For instance, when you type in words via the keyboard, the software is responsible for displaying the correct letters, in the correct place on the screen. Software is held either on your computer's hard disk, CD-ROM, DVD or on a diskette (floppy disk) and is loaded (i.e. copied) from the disk into the computers RAM (Random Access Memory), as and when required.

Information Technology (IT)

This is a general term which relates to the use of computers as an aid to creating and maintaining data, i.e. information. IT is related to all aspects of managing and processing information, especially within a large organization. Computers are critical to managing information, and computer departments within large organizations are often called IT departments. Alternative phrases are IS departments (Information Services) or MIS departments (Management Information Services). People working with computers within large companies will often refer to their job, as "working in IT".

Types of Computer

Mainframe computer

They are the big, powerful, expensive computers used in the background by most large organizations typically used to run the operations of an entire department or company

Network computers

They are computers that fit on an individual desktop, but they might not have much storage capacity. Instead, they rely on devices elsewhere on the network to store information for them.

PC (Personal Computer)

They ware invented by IBM in 1981 it is computers that fit on or under an individual desktop and that store their own information this type is probably the type of computer that you're most familiar with

Mac computer

The Apple Mac is a computer, but NOT a PC. It uses a different operating system, and requires special versions of application programs (such as word-processors or spreadsheets). Even the hardware add-ons have to be customized to some extent to be able to be connected to a Mac

Laptop computers

They are portable computers ranging in size from a briefcase to a small notepad they typically fold up to protect their screens when not in use

Personal Digital Assistants (PDAs)