Accountancy . . Central Processing Unit (CPU) This is the main part of computer hardware that actually processes data, according to the instructions it receives. It controls the flow of data by directing the data to enter the system, places the data into its memory, retrieves the same as and when needed and directs the output of data according to a set of stored instructions.
It has three main units as described below : (a) Arithmetic and Logic Unit (ALU) : It is responsible for performing all the arithmetic computations such as addition, subtraction, division, multiplication and exponentiation. In addition to this, it also performs logical operations involving comparisons among variables and data items. (b) Memory Unit : In this unit, data is stored before being actually processed. The data so stored is accessed and processed according to a set of instructions which are also stored in the memory of the computer well before such data is transmitted to the memory from input devices.
(c) Control Unit : This unit is entrusted with the responsibility of controlling and coordinating the activities of all other units of the computer system. Specifically, it performs the following functions : • Read instructions out of memory unit; • Decode such instructions; • Set up the routing of data, through internal circuitry/wiring, to the desired place at right time; and • Determine the input device from where to get next instruction after the instruction in hand has been executed. . .
Output Unit After processing the data, the information produced according to a set of instruction need to be made available to user in a human readable and understandable form. A computer system, therefore, needs an output device to communicate such information to the user. Essentially, the output device is assigned the task of translating the processed data from machine coded form to a human readable form. The commonly used output devices include: external devices like monitor also called Visual Display Unit (VDU), printer, graphic plotter for producing graphs, technical drawings and charts and internal devices like magnetic storage devices.
Recently, a new device being perfected is the speech synthesiser, which is capable of producing verbal output that sounds like human speech. Information: . Evolution of Computerised Accounting Manual system of accounting has been traditionally the most popular method of keeping the records of financial transactions of an organisation. © NCERT not to be republished