COMPUTER SYSTEM

Definition

A computer system is defined as an electronic device with a combination of components designed to accept(input) and process data according to specific rules(process) to produce results(output) which can be stored for future use(storage). A computer system consists of four major hardware components; input devices, output devices, processor and storage devices. A computer system requires hardware, software and a user to fully function.

Input - Input is any data or instructions that we enter into the computer system for processing. There are four types of input: which are text, graphic, audio and video. Example of input devices are keyboard, light pen, joystick, microphone, mouse, video & digital camera.

Process - The processing unit controls all activities within the system. The CPU is an

example of a processor. It has the same important as the brain to human being. The processor interprets and carries out the basic instructions that operate the computer. Example of processors or CPU are Pentium IV, AMD Athlon, G4.

Storage - Storage is a location which data, instruction and information are held for future use. It is the physical material that keeps data, instruction and information. There are two types of storage. They are the primary storage and secondary storage. The example of storage devices are RAM and ROM(primary storage), hardisk, Floppy Disk, diskette, CD ROM and DVD ROM(secondary storage).

Output - Output is data that has been processed into a useful form, called information. There are four types of output, which are texts, graphics, audio and video. Example of output devices are monitor, printer, speaker and plotter.

The information processing cycle

Input - Users input data or instruction into the computer system to be process. Input could be either text, graphic, audio or video. Input devices are used by users to input data. Input devices are any electronic device connected to a computer and produces input signals.

Process - Data or instruction being input into the computer system is then processed by the CPU which controls all activities within the system. The results of the processed data are then sent to an output device as usable data. Examples of CPU or processors are Intel Pentium 4, AMD K6 Athlon, Win Chip 2, Cyrix 686, Intel Celeron.

A CPU interprets the data and carries out the instructions by processing data and controlling the rest of the computer’s components. A CPU consists of two subcomponents; the Control Unit (CU) and the Arithmetic Logic Unit (ALU).

· CU or Control Unit main function is to direct the CPU to process data by extracting instructions from memory and decodes and executes them. It tells the rest of the computer system how to carry out the program’s instructions. It directs the movement of the electronic signals between the memory, which holds data, instructions and processed information, and the arithmetic logic unit. It also directs these control signals between the CPU and the I/O devices.

· The ALU or arithmetic-logic unit performs two types of operations: arithmetic and logic. Arithmetic operations are fundamental mathematical operations: addition, subtraction, multiplication and division. Logical operation consists of comparisons. That is two pieces of information or data are compared to see whether the result is equal, less than or greater than.

· The CPU manages a four-step basic operation which is called a machine cycle. The steps are Fetching, Decoding, Executing & Storing.

The Machine Cycle

Storage - Computer storage is important to help users store programs and data to be used at a later time. It is also useful to keep current data while being processed by the processor until the information is saved in a storage media such as a hard disk or a diskette. Computer storage also stores instructions from a computer program. There are two type of computer storage; primary storage and secondary storage.

• Primary storage is known as the main memory of a computer, including RAM (Random-Access Memory) and ROM (Read-Only Memory). It is an internal memory (inside the CPU) that can be accessed directly by the processor.
• Secondary storage an external storage that refers to various ways a computer can store program and data. Many complex functions, such as translators for high-level languages and operating systems are placed in primary storage. Secondary storage is an alternative storage. It is very useful to store programs and data for future use.

Output - Output is the result of data processing activity when it is presented external to the system. The output from a computer can be in a form for use by people, for example, printed or displayed. There are four types of output, which are texts, graphics, audio and video.