Information Technology Coursework Essay

Input The KeyboardThe divulgeboard is essenti in ally based on the standard QWERTY keyboard apply by typists. The main differences ar the put upitions make by computing machine manuf profes sure as shootingrs. The first topic to notice is that the keyboard has triple main sections. The first section is the main QWERTY keyboard, which has three extra keys. The most important of these extra keys is normally marked come in or RETURN. The enter key is on the right billet of the keyboard and is intaked to tell the ready reckoner that you waste finished typing and aspiration either to move to a fresh empty line or that you want the calculating machine to carry push through the typed management. The other two supererogatory keys ar the ALT and the CONTROL keys (CTRL). These act in the same route as the shift key on the typewriter and so allow form keys to have a number of contrary effects.The second divorce of the keyboard is the officiate keys. There are al expressiv e styles at least ten and some propagation twelve of these labelled F1 to F10 or F12, which are grouped together on the left of the keyboard or along the top of it. They are apply by weapons platforms handle word mainframes or spreadsheets to give educational activity manual to the figurer. They do not normally produce an effect on the cover version but burn do in some programs.The third part of the keyboard is the numeric key pad. This is situated on the right of the keyboard and serves two functions. Firstly, to move the cursor and second to type numbers racket into the ready reckoner. The keys on the keypad usually contain the numbers 0 to 9, the decimal point and the mathematical symbols. The key marked NUMLOCK is used to tell the estimator if the pad is used to enter numbers (NUMLOCK ON) or to move the cursor (NUMLOCK OFF).Input The MouseA mouse is a device, which gage provide an alternative to the keyboard. The mouse itself has a bantamer junkie in its base whic h, when pulled across a smooth step forward, moves a finical cursor across the screen. This cursor green goddess be used to sweep up or point and is especially effective in providing an easy to use interface for those who have difficulty with keyboards etc.process The of import Processing UnitInside the microcomputer is a tiny silicon arrest called the Central Processing Unit or central processor this can be regarded as the brain of the entire formation. With the help of the computers familiar memory it exe write upes the instructions in a program by execute simple logical operations at very high speeds typically an instruction exit be performed in millionths of a second.The chip containing the Central Processing Unit or CPU is the place where the computer does its persuasion. The CPU processes tuition by fetching a program instruction retentiond in the computers memory, executing the instruction and proceeding to the contiguous step in the program. The CPU conta ins (1) a program counter that tells the CPU where it is in the program. (2) an instruction register that stores the current program instruction. (3) a check out unit that decodes the contents of the instruction register. (4) learning registers that store the small units of cultivation the CPU is currently treat. (5) a memory channelize register that holds the address or memory location of the instruction in its data registers. (6) an arithmetic and Logic Unit (ALU) that actually performs each small step in the program, and (7) a status or flags register that reports on the work of the ALU. The coat or power of a CPU is determined by the continuance of its registers 8-bit processors work on in data formation in 8-bit groups 16-bit processors have registers that hold 16 bits and are twice as fast. 32-bit processors provide even more work out speed, and so on.Internal Memory RAM and ROMBecause the central processing unit just now works on small pieces of training at a ti me, the computer needs a way to store information while it is not being processed. Two kinds of silicon chips serve as the computers internal memory. Random Access Memory or RAM chips store information temporarily, and the computer can write, read, and erase information on them. RAM chips are erased every time the computer is sour off, so Read Only Memory or ROM chips act as the computers permanent memory they store the instructions the CPU needs when you first turn it on.External Memory discs and Disk DrivesExternal memory devices like floppy platters, hard dish antennas, and CD-ROMs store programs and data when the computer is turned off. When a disk is inserted into a disk drive, the computer can read information from it or write new information onto it. Only certain types of CD-ROM can have information indite onto them.Output The PrinterPrinters receive electrical codes from the computer and and then print the corresponding letter or number on paper. The result is calle d hard copy. Plotters and some printers can even reproduce computer graphics on paper.Types of PrinterInk Jet PrintersInk jet printers work as their name suggests, by squirting jets of ink onto the paper by dint of tiny nozzles. Ink-jets provide good quality widening (on average 600 dots per inch) at average speed and at relatively low cost.Laser PrintersA optical maser printer is essentially a photocopier attached to the computer as an production device. Laser printers are capable of high quality yield ( virtually 720 dots per inch), at high speed. They can be bought from as little as around 100.Output Monitors (Visual Display Units)Monitors (V.D.U.s) are the most frequently used output device. The display is transmitted from the computer to the surface of a cathode ray tube, which is sort of like a television screen. Slim, flat screen monitors are likewise available. The display consists of very small phosphorescent dots combined in diametric patterns to form words, numbe rs, and pictures. Monitors vary in their resolution (clarity), more dots on the screen means a higher resolution but obviously cost more. The range of resolutions are CGA, EGA and the highest resolution VGA.Software Computer ProgramsA program is simply a set of instructions, which the programmer wishes the computer to obey. The computer blindly obeys any instruction which it is abandoned it possess no abilities to determine whether an instruction (so long as it is framed correctly) is the correct instruction for any given situation. Programs tell the computer how to turn the input you provide into the output you want. A program is therefore a detailed set of instructions for acting a particular task. Because you cannot actually touch programs they have become cognise as parcel this contrasts with the computer hardware of a computer system monitors, chips, printers etc. which you can touchSoftware takes many forms the computer system itself is co-ordinated by a special resid ent program called an operating system (you can read more about this program below), programs to carry out special tasks for the user are termed application programs. Stock take hold, word processing, payroll and write up functions are typical areas, which are serviced by application programs.Input/output Media Mass StorageFloppy DisksA floppy disk is 3 1/2 inches square. Inside its protective case or sleeve, each floppy disc is a circle of flexible plastic whose surface is covered with magnetized oxide. When you use a disc for the first time, you moldiness use a special program called an operating system to format the disks surface by creating circular tracks divided into pie-shaped arenas. A welter punched near the hub of the disk lets the computer know where the first sector is. A track on each disk stores a directory that tells the computer where to follow what information. This means that it can go directly to the correct part of the disk instead of wading through all o f its contents to find the information it wants. A typical floppy disk can store around 200 pages of typewritten text, dep obliterateing on how tightly the information is packed. If pictures are stored on disk, they take up a lot of room.Care of Floppy Disks reading is stored on floppy disk by means of magnetism. The information stored on a disk can be lost if the magnetic surface of the disk is damaged. When handling a disk you must be watchful not to bend it or touch the exposed portions. Moisture, extreme temperatures, and word-painting to magnetic fields or equipment can also ruin disks. You should defy clog up-up copies of all important disks to insure that your data will not be lost if a disk is damaged. You can guard against the possibility of by luck writing over and erasing important data and programs by moving the small write-protect notch on the side of the disk. When this notch is closed, a sensor within the drive prevents the head from writing onto the disk.Hard Di sks farely modern PCs have hard disks, which can store vast come ins of information this varies depending upon their size. Although they operate on the same basic principles as floppies, hard disks spin many times more quickly allowing the read/write head to pass only fractions of an inch over the disks surface. Hard disks are hermetically sealed in special chambers to prevent dust particles from ruin the disks surface.Disk Drives Read/Write HeadsTo use a disk, you place it into a disk drive so that the circular hole in the centre of the disk fits into a strobilus in the drive. This cone spins the disk allowing all of its sectors to come under a window cut into the sleeve. As the disk spins around, a read / write head moves back and forth over the exposed portion of the disk. The head works like the head on a tape rec parliamentary procedure. It reads information on the disk by translating its magnetic fields into electrical signals that are sent to the computer information is w ritten onto the disk when the head converts the electrical signals from the computer into magnetic fields on the disks surface.Operating SystemsA computer is really a system of interconnected parts a keyboard or input device internal memory (RAM and ROM) a processor disks and disk drives output devices like a monitor and a printer and, of course, software. A special kind of program called an operating system controls the flow of information between these different components. One of its most important jobs is to enable your hardware to understand the instructions of your software. When you buy a computer, you must be sure that its design or architecture is compatible with the operating system for which the software you want is written. The operating system manages the files on your disks and offers utilities such as data formatting blank disks, listing the directory of files on a disk, as well as copying, renaming, and deleting files. Sometimes operating systems are permanently ins talled, but if the operating system is pre-packaged on a disk, its contents must either be soused each into the computer or written onto every disk used, during the formatting process. Windows 95 and Windows 98 are the most common operating systems used today.Modems and NetworksWith the help of a modem, your computer can link up and blow over with other computers all over the world. The modem translates the computers language of ons and offs into tones of different frequencies, which are then transmitted across mobilise lines. At the receiving end the process is reversed a modem converts tone variations back into the computers digital code. Computer networks are systems of computers linked together in this way they are used to send and receive electronic mail, and to allow small personal computers access to the vast data libraries of larger computers, via the Internet.COMPUTER APPLICATIONS cover PackagesThese are programs that actually perform the tasks that the user wishes to b e done. The tasks are usually so complicated that several programs are required and these are jointly called a suite of programs. Typical illustrations of applications are Stock Control, Databases, Order Processing, give voice Processing, Airline Booking Systems, Spreadsheets, Viewdata Systems and Point of Sale Systems. each package will now be discussed in turn, to give a general news report of what they are, when they are used and for what purpose.Stock ControlA stock control system keeps track of all the stock currently held by the company. The computer is informed through the till when each item is sold. It is then an easy matter to deduct the number sold from the current stock direct to give a new stock level. If this level is below a re-order level which again is held by the computer, then the computer can automatically print a re-order letter to the supplier.The number of each item to be supplied is stored and when the supplier delivers, the number of items delivered is added to the amount in stock. Therefore the company, in theory, should never, through its own efforts, run out of any item of stock and should at all times know how much stock it has, in the warehouse, in storage at a retail outlet and on the shelves. losings through theft are easily calculated through a manual shelf count, and corrective action to reduce losses can be implemented quickly.DatabaseA database is a store of information made up of records. A record contains information relating to one person or one company and is made up of individual pieces of information called fields. For example, you may create your records having the following fields company name, address, telephone number, credit limit, amount owed, payment due etc.When all the information has been entered the database may then be used by searching for particular information, called cross-referencing (e.g. to find out at the end of the month who the company owes money to and how much, in order to settle their ac counts). New information can be fed in and the database is changed (updated) to include the new data, so that it is always up to date. Large databases are best used with static information (remains the same), with new records being added to the end. An example of this type is a Library with records on all the books in stock.The computer operated by the DVLA in Swansea (Driving Vehicle Licensing Authority) might be an example of a large database. Information relating to every motor vehicle in the U.K. is stored on computer and can be sorted or searched to find out, for example, who owns a particular car.Word ProcessingIn word processing a computer behaves like a much enhanced form of typewriter. Facilities are provided for entering, manipulating, storing and retrieving blocks of text. This means that standard letters and lists of names and addresses can be generated separately and then letters to everyone on the list can be printed without retyping the document. The processor retriev es the letter and the first name and address, prints the letter, retrieves the next name and address, changes the information in the letter, prints the next letter and so on.Real-Time SystemsAn example of a real time system is Airline Booking. This is a system which updates the data immediately it changes. All the terminals in all the booking shoess are connected via a telephone line to a large computer in the head office of the company. This is so that information can be accessed immediately and be changed on bank check of a booking immediately. For example, if you wanted to book a flight of steps, you would execute details into the terminal about the flight, and back would come a substance saying perhaps that only two seats remain on that flight. If you then take these seats by sending that information back, confirmation would take place and then no-one anywhere in the world would be able to book a seat on that particular flight (even if they tried to book only ten seconds aft er you).SpreadsheetA spreadsheet is a special application package, which allows the user to set up tables of information and add up rows and columns which make up the table. They are used mainly for displaying interchange forecasts of companies, in the form of a table where all the figures are interconnected. Each intersection of a row and a column is called a prison cell. The cells are filled with figures and then changes can be made and the spreadsheet calculates all the related cells, alters and reprints them. Figures can be changed and the overall effect on the complete table can be seen immediately.