Info-Grade: Von Neumann's architecture

Computer System and John Von Neumann's architecture of computer system

What is computer system? Discuss its components. Explain John Von Neumann's architecture of computer system.

A computer system is a set of integrated devices that input, output, process, and store data and information. Computer systems are currently built around at least one digital processing device. There are five main hardware components in a computer system: Input, Processing, Storage, Output and Communication devices.

Input

Input means data and instruction given to the computer which is most essential for producing meaningful and useful output. The unit which is used to give input to the computer system is called input unit and it is formed by various input devices attached to the computer such as keyboard, mouse, joystick, trackball touch screen, MICR (Magnetic Ink Character REader) etc into computer understandable form. The input unit establishes the communication link between the user and the computer system.

Processing

Processing unit is also called 'Central Processing Unit' and it is the control center for a computer. It guides, directs and governs all operations and components inside the computer. It is considered as brain of computer. It is linked with various peripheral devices including I/O devices, secondary storage and memory unit. it performs arithmetic operations, logical comparison, transfer information between all parts of computer and executes instructions. CPU consists of ALU, CU and Registers.

Output

Output is the processed data which is very useful and meaningful to us and we can get it from the computer in the form that we want. The unit which is used to provide output is called output unit. It is always in the form of human readable or understandable. There are various types of output devices such as Monitor, Printer, Plotter, Speakers etc.

Memory/Storage Unit

A storage device is any computing hardware that is used for storing, porting and extracting data files and objects. It can hold and store information both temporarily and permanently, and can be internal or external to a computer, server or any similar computing device. Data and instruction are stored in memory in the binary form.

Von Neumann Architecture

Von Neumann architecture is based on the stored-program computer concept, where instruction data and program data are stored in the same memory. This design is still used in most computers produced today. This architecture was first published by John von Neumann in 1945.

Von Neumann Architecture

His computer architecture design consists of a Control Unit, Arithmetic and Logic Unit (ALU), Memory Unit, Registers and Inputs/Outputs.

CPU (Central Processing Unit)

The CPU is an electronic circuit which is responsible for executing the instructions of a computer program. Sometimes it is also referred to as the microprocessor or processor. It contains ALU, CU and Registers.

Registers

Registers are high speed storage areas in the CPU. All data must be stored in a register before it can be processed. Some registers are

MAR (Memory Address Register)
MDR (Memory Data Register)
AC (Accumulator)
PC (Program Counter)
CIR (Current Instruction Register)

ALU (Arithmetic and Logic Unit)

The ALU allows arithmetic (add, subtract etc) and logic (AND, OR, NOT etc) operations to be carried out.

CU(Control Unit)

The control unit controls the operation of the computer’s ALU, memory and input/output devices, telling them how to respond to the program instructions it has just read and interpreted from the memory unit.

MU (Memory Unit)

The memory unit consists of RAM, sometimes referred to as primary or main memory. Unlike a hard drive (secondary memory), this memory is fast and also directly accessible by the CPU.

Buses

Buses are the means by which data is transmitted from one part of a computer to another, connecting all major internal components to the CPU and memory. There are three types of buses