Block diagram of digital computer:

The general pattern of computer architecture has remained unchanged over the last four decades or so. It has a single processor, which accepts data from an input device or obtains it from backing storage, performs some operations on it, and returns the processed data to storage or to an output device. Information is passed between the components by means of a high speed data channel, (see the block diagram of a digital computer) known as a bus. The operation is serial, with a single operation being performed on a single data item.  

The result is a general purpose computer, able to be used for different tasks. Over the years many improvements have been made to this sort of computer to improve its speed and power. One example is the emergence of RISC (Reduced Instruction Set Computing) machines, which give faster performance for some types of applications by using a smaller set of machine instructions. It maybe mentioned that the main change in computer architecture that is now widens/ay is the emergence of parallel processing. In other words, parallel processing machines can perform the same operation on a number of data items at a time, or may have a number of processing units operating independently, performing different operations on different data items simultaneously. Parallelism has been first developed for super-computers. However, the parallelism requires special software for its applicability. Hence its utility is somewhat limited. It may be mentioned that parallel processor machines are now beginning to be used for database applications. Parallel processing is now becoming generally available in the form of transputer which can be attached with or added to microcomputer systems to improve their performance. Most of the professionals seeking to automate some aspects of information management will be using microcomputers. However, it is desirable to know developments in larger machines.