Q. Explain the typical organization of a computer?

There are two principal components: hardware and software. The former refers to physical components such as memory unit (MU), arithmetic and logic unit (ALU), control unit (CU), input/output (I/O) devices, etc.; whereas the latter refers to the programs (collections of ordered instructions) that direct the hardware operations.

Figure illustrates the basic organization of a digital computer. TheMU stores both data and programs that are currently processed and executed. The ALU processes the data obtained from the MU and/or input devices, and puts the processed data back into the MU and/or output devices. The CU coordinates the operations of the MU, ALU, and I/O units. While retrieving instructions from programs resident in theMU, the CU decodes these instructions and directs the ALU to perform the corresponding processing; it also oversees the I/O operations. Input devices may consist of card readers, keyboards,magnetic tape readers, andA/Dconverters; output devices may consist of line printers, plotters, and D/A converters. Devices such as terminals andmagnetic disk drives have both input and output capabilities. For communicating with the external world and for storing large quantities of data, a variety of I/O devices are used.

Software may be classified as system software and user software. The former refers to the collection of programs provided by the computer system for the creation and execution of the user programs, whereas the latter refers to the programs generated by various computer users for solving their specific problems.