Composition of A Computer

The computer is made up of two main parts known as the Hardware and Software, and this basically is classification based on whether or not we can touch that particular part of the computer. HARDWARE: This refers to the various components that come together to make up the computer (PC). The term is generally used to indicate any part of the PC that can be physically touched. Hardware is also classified into to two parts namely System Unit and Peripherals. • System Unit: The system unit is the main component of the PC to which other components are connected. It is made up of: 1. Mother board: This is a single printed circuit which holds the essential electronic components of the system unit. It holds the microprocessor, the memory chips (Rom and Ram) and any other microchip required for the computer to function. 2. Microprocessor: this is the main brain of the PC. It can execute millions of instructions every second thus making the PC a powerful tool. The microprocessor also known as the CPU (Central Processing Unit) performs the following functions. A) Carries out commands to make the hardware components perform actions. B) Processing of data, this involves; performing logical instructions such as comparing and performing mathematical instructions such as adding and subtracting etc. 3. Memory (RAM and ROM): There are two types of memories within every PC. A) RAM (Random Access Memory): this is component is found in the system unit. It can be read from and written to, it is high speed compared to the ROM, looses information when power is lost and it is used mostly by the system board, video cards etc. The microprocessor uses the system RAM for the temporal storage of date. Unlike disk drives any information within the RAM will be lost when the PC looses its power. The RAM holds data, and information (processed data) to be output. The reason why it is called “Random Access” memory is that data can be retrieved at random from anywhere in a RAM chip in equal amount of time. RAM is also known as Primary storage. B) ROM (Read Only Memory): this component is slower that practically all types of RAM. ROM contains programs or instructions , which the computer accesses to manage the flow of information within it. The PC, user cannot change the contents of the ROM. The manufacturer on the system board installs the ROM chips also called FIRMWARE. They store instructions in permanent or non-volatile form. Non-volatile storage does not loose its contents when the power is turned off. 4. Disk Drives: These are the permanent storage area of the PC where data can be stored for a long period of time. Storage is a term used for devices or mediums that can accept data, hold the data, and deliver it on demand at a later date. In this section, we will discuss secondary storage. Secondary storage or auxiliary storage is permanent storage. This storage is non-volatile; the contents still exist after the power is turned off. The materials on which data and instructions are stored as electromagnetic signals are called media or storage media. If data held in Ram is to be kept permanently, it should be saved to a disk drive. A disk drive can be divided into logical areas called directories (or folders); these are used to hold the files that contain your data. A) Floppy Disk: This is a circular disk made of flexible plastic, which is coated in a magnetic material and held inside a hard plastic case B) Compact Disk: (CD- Rom) these drives are now supplied with most new PCs, A CD-ROM cannot be written to. However Re-writeable Cd technology has made it possible now to write to the CD-ROM and the re-writeable CD is becoming cheaper. C) Hard Disk Drive: A hard disk is made of glass or metal , as opposed to the flexible plastic from which floppy disk is made. It is mounted in a sealed unit usually fixed disk drives, hard disk is one of the mediums of storing information permanently. 5. Power Supplies: The power supply is responsible for converting the incoming electricity to other components of the PC. Devices such as CD-ROMs and floppy drives are connected to the power supply using “Molex” or “ mini Molex “ connectors. The system board connectors are known as P8 and P9. • PERIPHERALS 1. Input peripherals: are devices, which can send information to the CPU e.g. (keyboard, mouse, mike, scanner etc. 2. Output peripherals: they are devices, which displays the results delivered by the CPU after processing the instructions or commands given to it e.g.(monitor, printer, speaker, etc.) 3. In/Out peripheral: they are devices, which can send and retrieve information from the CPU e.g.( modem), CD-ROM drives, floppy disk. SOFTWARE There are two types of software namely Application Software and Operating System Software. A) Application Software: This is the kind of software that people use to perform a general purpose task, as work processing software. B) System Software: Is the software that works behind the scenes to manage the internal activities of the computer and serve as platform to run application software. E.g. Mac OS, MS- DOS, Windows XP, OS/2.