Information Technology Coursework Essay

Input The KeyboardThe keyboard is essenti completelyy based on the standard QWERTY keyboard enjoyment by typists. The chief(prenominal) differences ar the additions made by calculating machine manufacturers. The first thing to notice is that the keyboard has three main sections. The first section is the main QWERTY keyboard, which has three extra keys. The nearly important of these extra keys is usu all in ally tag ENTER or RETURN. The enter key is on the right side of the keyboard and is employ to branch the figurer that you have finished typing and wish either to move to a fresh annul line or that you want the estimator to ask extinct the fontd instruction. The other two additional keys ar the ALT and the CONTROL keys (CTRL). These act in the same way as the shift key on the typewriter and so allow normal keys to have a number of different effects.The second spell of the keyboard is the act upon keys. There ar always at least ten and sometimes twelve of these lab elled F1 to F10 or F12, which be grouped together on the left of the keyboard or along the top of it. They are used by courses like word processors or spreadsheets to give instructions to the reckoner. They do not normally garden truck an effect on the screen precisely cigaret 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 secondly to type numbers into the computer. The keys on the keypad usually contain the numbers 0 to 9, the decimal show and the mathematical symbols. The key marked NUMLOCK is used to tell the computer 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 bay window provide an choice to the keyboard. The mouse itself has a small ball in its base which, when pulled across a smooth surface, moves a circumscribed cursor across the screen. This cursor can be used to draw or point and is especially effective in providing an easy to use interface for those who have difficulty with keyboards etc. bear on The substitution Processing UnitInside the microcomputer is a tiny silicon chip called the Central Processing Unit or CPU this can be regarded as the brain of the entire schema. With the serve up of the computers internal reminiscence it exe curles the instructions in a program by acting simple logical operations at very high speeds typically an instruction will be performed in millionths of a second.The chip containing the Central Processing Unit or CPU is the ass where the computer does its thinking. The CPU processes tuition by fetching a program instruction hold ond in the computers memory, executing the instruction and proceeding to the next step in the program. The CPU contains (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 control whole that decodes the contents of the instruction register. (4) selective instruction registers that store the small units of entropy the CPU is currently processing. (5) a memory address register that holds the address or memory location of the information in its data registers. (6) an arithmetical and Logic Unit (ALU) that real performs severally small step in the program, and (7) a status or flags register that reports on the croak of the ALU. The size or power of a CPU is determined by the length of its registers 8-bit processors work on information in 8-bit groups 16-bit processors have registers that hold 16 bits and are double as fast. 32-bit processors provide nevertheless more computing speed, and so on.Internal Memory RAM and read-only memoryBecause the central processing unit only works on small pieces of information at a time, the computer of necessity a way to store information while it is not being processed. twain kinds of silicon chips serve as th e 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 turned off, so Read Only Memory or read-only storage chips act as the computers permanent memory they store the instructions the CPU needs when you first turn it on.External Memory Disks and Disk DrivesExternal memory devices like lax saucers, rough magnetized dish aerials, 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 compose onto them.Output The PrinterPrinters receive electrical codes from the computer and then brand the corresponding letter or number on paper. The result is called hard copy. Plotters and some bring outers can even reproduce computer graphics on paper.Types of P rinterInk Jet PrintersInk jet printers work as their name suggests, by squirting jets of ink onto the paper by means of tiny nozzles. Ink-jets provide approximate quality siding (on average 600 dots per inch) at reasonable speed and at relatively low cost.laser PrintersA laser printer is essentially a photocopier attached to the computer as an output device. optical maser printers are capable of high quality output (around 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 transmit from the computer to the surface of a cathode ray tube, which is rather like a television screen. Slim, flat screen supervises are withal available. The display consists of very small phosphorescent dots combined in different patterns to form words, numbers, and pictures. Monitors vary in their resolution (clarity), more dots on the screen means a hig her resolution but obviously costs more. The range of resolutions are CGA, EGA and the highest resolution VGA.Software calculating machine ProgramsA program is simply a set of instructions, which the programmer wishes the computer to obey. The computer blindly obeys every instruction which it is given it possess no abilities to determine whether an instruction (so long as it is framed subduely) is the correct instruction for any given situation. Programs tell the computer how to turn the arousal you provide into the output you want. A program is therefore a detailed set of instructions for performing a particular task. Because you cannot actually touch programs they have become known as software this contrasts with the hardware of a computer clay monitors, chips, printers etc. which you can touchSoftware takes umpteen forms the computer formation itself is co-ordinated by a special resident program called an operating system (you can read more about this program below), p rograms to carry out specific tasks for the user are termed application programs. sprout control, word processing, payroll and accounting 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 c everywhereed with magnetic oxide. When you use a disc for the first time, you must use a special program called an operating system to format the disks surface by creating circular tracks divided into pie-shaped sectors. A hole punched tight-fitting 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 find what information. This means that it can go directly to the correct part of the disk instead of wading through all of its contents to find the information it wants. A typical floppy disk can store ar ound 200 pages of typewritten text, depending on how tightly the information is packed. If pictures are stored on disk, they take up a lot of room.Care of Floppy DisksInformation is stored on floppy disk by means of magnetism. The information stored on a disk can be confused if the magnetic surface of the disk is damaged. When handling a disk you must be careful not to turn it or touch the expose portions. Moisture, extreme temperatures, and exposure to magnetic fields or equipment can also ruin disks. You should keep back-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 accidentally 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 inside the drive hinders the head from writing onto the disk.Hard DisksAll modern PCs have hard disks, which can store vast amounts 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 ruining 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 c 1 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 recorder. It reads information on the disk by translating its magnetic fields into electrical signals that are sent to the computer information is written onto the disk when the head converts the electrical signals from the computer into magnetic fields on the disks su rface. in operation(p) SystemsA computer is really a system of inter connected 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 procure 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 formatting blank disks, tilt the directory of files on a disk, as well as copying, renaming, and deleting files. Sometimes operating systems are permanently installed, but if the operating system is pre-packaged on a disk, its contents must either be loaded one after another 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 travel by with other computers all over the cosmea. The modem translates the computers language of ons and offs into tones of different frequencies, which are then transmitted across telephone 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 APPLICATIONSApplication PackagesThese are programs that actually perform the tasks that the user wishes to be done. The tasks are usually so complicated that several programs are required and these are co llectively called a suite of programs. Typical examples of applications are Stock Control, Databases, Order Processing, Word Processing, airline business Booking Systems, Spreadsheets, Viewdata Systems and Point of Sale Systems. Each package will now be discussed in turn, to give a general explanation 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 set out the number sold from the current stock take aim 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 ow n 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. Losses through theft are easily calculated through a manual shelf count, and corrective action to reduce losses can be apply 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 wee 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 accounts). 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. pear-shaped 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 scripts 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 retrieves 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 offices 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 confirmation of a booking immediately. For example, if you precious to book a flight, you would feed details into the terminal about the flight, and back would come a pith saying perhaps that only two seat 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 after you).SpreadsheetA spreadsheet is a special application package, which allows the user to set up tables o f information and add up rows and columns which make up the table. They are used mainly for displaying cash 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 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.