Over view
“In 1951, Van Neumann and his team proposed a design of a stored program computer. According to his design a sequence of instructions (called a Program) and the data are stored in the memory of the machine. The machine reads the instructions one by one and executes these instructions accordingly. This seemingly simple design is proved to be very powerful and general purpose. It is the basis of most modern day computers.
If we consider the architecture of the modern stored program machine the following are most important components are:
Control Unit(CU): The control unit reads the instructions from the memory and decodes these instructions. This unit uses other components of the computer to execute the instructions given to the computer
Arithmetic and Logical Unit (ALU): As the general-purpose computer can perform different arithmetic operations on the data so it has a special unit that has electronic circuits to perform the basic arithmetic and logical operations on the data. This is called the Arithmetic and Logical Unit or ALU.
Main Memory: The stored program computer has another very important component that is use to store program and data while these are being executed. This is commonly known as the Main Memory of the computer. Sometimes we also call it the working area of the computer.
I/O Unit: This handles the processor’s communication with its peripherals. For example, Disc drive, monitor, printer etc. There are registers to hold the data coming in or going out and peripheral device selection unit which determines which interface to send the data to. As the data and instructions should be in the memory before the computer can start executing it so to place data and instructions in the memory this stored program computer also has some I/O devices.
Bus Interconnection: This is another important component of the basic architecture and this component is used to connect different parts of the computer together.
The figure given below clearly the main components in the architecture of the computer.
