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Identify the constituent parts of a total computer system.

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Identify the constituent parts of a total computer system: Hardware - input and output units Backup storage; central processing unit; Software - applications package; Operating system; The main function of a computer system is to process data. When data has been processed and output it becomes information. The main stages of this procedure are: 1. The Input Stage - where data is put into the computer. 2. The Processing Stage - where the data is processed. 3. The Output Stage - where the results are displayed. A computer also needs to store data for later use. This is done on a backing storage device. Hardware - input and output units INPUT DEVICES Barcode reader Barcodes are different groups of vertical bars that can be read by an optical scanner. Barcodes are printed on nearly every product that you can buy. Shops use barcodes because they are cheap to produce and very durable. Concept keyboard A concept keyboard is a flat board that contains a grid of buttons. Each button can be programmed to follow instructions. An overlay sheet is placed on the grid with an explanation for each button. They are used in primary schools with young children. Many modern fast food restaurants have overlays with either a description or picture of the meals that are available to make ordering easier. Digital camera A digital camera allows you to take pictures and to store a digital photographic image that can be read by a computer. ...read more.


As CD-ROMs are much bigger than floppy disks, they can be used for multimedia applications such as encyclopaedias and can store pictures, sounds and video clips. It is now possible to record on to CDs with a CD writer. Backing store - magnetic tape Magnetic tapes or cartridges are principally used for backup. As they are small, robust and portable, with the ability to store far more than a floppy disk, they are often used to back up important documents and files from the hard-drive. Magnetic media is also used for long term storage and the archiving of data. CENTRAL PROCESSING UNIT CPU stands for Central Processing Unit. It is the 'brain' of the computer. In fact, it is a microprocessor (chip) fixed to a circuit board inside the computer. There are three main parts of the CPU - 1. The A.L.U. (Arithmetic and Logic Unit), which does all the arithmetic and logical operations. 2. The Main Store Memory. This is where data and programs are stored. 3. The Control Unit. This is the part, which controls the sequence of all computer operations. Arithmetic Logic unit is the part of the computer where all calculating and testing happens. Data is sent to and received from the the ALU by the control unit. Computer memory can be divided into two main types, main store and backing store. ...read more.


The term usually applies to mainframe operation when the computer is switching between a number of different programs or dealing with a number of different users. The jobs are usually given priorities. The operating system switches jobs in and out of processor time according to priority. For example, while one job is being allocated printer time, another will be being processed in memory. The processor is so fast that it seems that many jobs are being processed at the same time. Multitasking Multitasking usually applies to microcomputers whereby the computer is running a number of applications apparently at the same time. Multi-access or multi-user A multi-access (or multi-user) system is one where a number of users work with terminals on-line to a central computer. The central processor deals with users in turn; clearly the more users, the slower the response time. Generally, however, the processor is so fast that the response time at the most is a fraction of a second and the user feels they are being dealt with immediately. Batch processing A batch processing system is where programs or data are collected together in a batch and processed in one go. Typically the processing of payrolls, electricity bills, invoices and daily transactions are dealt with this way. This method of operation lends itself to jobs with similar inputs, processing and outputs where no human intervention is needed. Jobs are stored in a queue until the computer is ready to deal with them. Often batch processed jobs are done overnight. ...read more.

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