Basic Computer Organization




Basic Computer Organization

Even though the size, shape, performance, reliability, and cost of computers have been changing over the last several years, the basic logical structure (based on the stored program concept), as proposed by Von Neumann, has not charged. No matter what shape and size of computer we are talking about, all computer systems perform the following five basic functions for converting raw input data into useful information and presenting it to a user.

  • Inputting. It is the process of entering data and instructions into a computer system.

  • Storing. It is the process of saving data and instruction to make them readily available for initial or additional processing as when required.

  • Processing. Performing arithmetic operations (add, subtract, multiply, divide, etc.) or logical operations (comparisons like equal to, less than, greater than, etc.) on data to convert them into useful informations is known as processing.

  • Outputting. It is the process of producing useful information or results for a user, such as printed report or visual display.

  • Controlling. Directing the manner and sequence in which the above operations are performed is known as controlling.

The goal of this chapter is to familiarize you with the units of a computer system that perform these functions. It provides an overview of computer systems as computer system architects view them. Internal architecture of computers differs from one system model to another. However, basic organization remains the same for all computer system.

INPUT UNIT

Data and instructions must enter a computer system before the computer can perform any computation on the supplied data. The input unit that links a computer with its external environment performs this task. Data and instructions enter a computer through an input unit in a form that depends upon the input device used. For example, data can be entered using a keyboard in a manner similar to typing and this differs from the way in which data is entered through a scanner, another type of input device. However, a computer's memory is designed to accept input in binary code and hence, all input devices must transform input signals to binary codes. Units called input interfaces accomplish this transformation. Input interfaces match the unique physical or electrical characteristics of input devices to the requirements of a computer systems.

In short, an input unit performs following functions:-

  • It accepts (or reads) instructions data from outside world.

  • It converts these instructions and data in computer acceptable form. Units called input interfaces accomplish this task.

  • It supplies the converted instructions and data to the storage unit for storage and further processing.

OUTPUT UNIT

An output unit performs the reverse operation of that an input. It supplies information obtained from data processing to outside world. Hence, it links a computer with its external environment. As computers work with binary code, results produced are also in binary form. Therefore, before supplying the results to outside world, the system must convert them to human acceptable(readable) form. Units called output interfaces accomplish this task. Output interfaces match the unique physical or electrical characteristics of output devices (terminals, printers, etc.) to the requirements of an external environment.

In short, an output unit performs following functions:-

  • It accepts the produced results, which are in coded form. We cannot understand the coded results easily.

  • It concerts these coded results to human acceptable (readable) form. Units called output interfaces accomplish this task.

  • It supplies the converted results to outside world.