Functions of different parts of computer system is segregated based on its activities: All digital computers provide for four major activities:
(1) input-output for transferring information into and out of the computer,
(2) storage or memory where figures and facts are accessible,
(3) processing or calculating, the arithmetic and logic unit, where operations are performed on the stored data, and
(4) control for coordinating other units in the system to perform the instructions and desired sequence of operations.
(1) Input-Output unit under the Functions of different parts of computer system:
An input unit working from punched cards, punched paper tape, magnetic tape, magnetic ink, or other media feeds the data and processing instructions into the storage unit. The original data may come from purchase requisitions, invoices, time tickets, sales tickets, as well as from journal vouchers. The output system, a printer, prints out results at the conclusion of processing as instructed in the program, thereby providing rapid feedback to managerial personnel.
(2)Storage unit under the Functions of different parts of computer system:
The computer stores information on magnetic tapes, magnetic cores, or magnetic disks. Computer storage can be regarded as a completely indexed electronic filing cabinet in many cases instantaneously accessible to the computer. Characters or digits of information are stored on tiny magnetized spots or cores in code form, and the data are processed electronically at very high speed to provide the computer with the information it seeks.
(3) Arithmetic and Logic Unit (ALU) under the Functions of different parts of computer system:
From its almost unbelievably complete electronic filing cabinet, the arithmetic and logic unit of a computer system follows instructions to select data from storage and to make desired computations or arrangements. This is done by electronic circuits at the speed of light.
(4)Control Unit unit under the Functions of different parts of computer system:
A control panel or unit reads instructions and informs the computer where the desired data are stored, what data are required, and what sequence to follow. The computer can guide itself through a continuous series of instructions or programs, call data from storage and process it, return it to storage, and direct the output printer to print out of the final results or report as directed. A console permits the operator to communicate with and manually control certain functions of a digital computer, such as start and stop the machine, regulate input and output units, and direct other operations of the system.
In essence, a computer system immediately converts the original document from every business transaction to computer language and files it. Then, as instructed, the computer reaches into its file and completes all further actions required in connection with the transaction, along with summary reports of all transactions classified in any way most useful to management.