Block Diagram of Computer

The basic block diagram of computer was proposed by Von Neumann

Data:

Data is raw material which is unprocessed for data processing. It is normally entered by input devices into computer and it can be in any form, usable or not.

nformation:
I

Information is data that has been processed. It can be useful for the person receiving since it brings meaning.

It can understand by user. Information is processed data obtained as output of data processing.

Program:

Program is a set of instruction that tells the computer what to do.

Input Unit:

All data and instructions need to be entered into the computer system through the input unit.

Ø Accepts the data and instructions from the outside world.

Ø Converts the data and instruction into a form that computer can understand.

Ø The converted data and instructions are sent to the computer system for further processing.

Storage Unit:

The basic unit of storage in as computer is bit. Bit is binary digit which can be set to either 0 or 1.

The memory is comprised of a large number of individual cells, each with a unique number, known as its address, associated with it.

The storage capacity of a computer is measured in terms of bytes; 1 byte is equal to 8 bits.

Measured	Bytes	Bytes
1KB	1024	210
1MB	104876	220
1GB	1073741824	230

Primary Storage

It stores and provide very fast. This memory is generally used to hold the program being currently executed in the computer.

The data being received from the input unit, manipulated the data and final results of the program. The primary memory is temporary in nature.

The data is lost, when the computer is turned off. In order to store the data permanently, the data has to be transferred to the secondary memory.

It is the only one directly accessible to the CPU. The CPU continuously reads instructions stored there and executes them as required.

Secondary Storage

Secondary storage is used like an archive. It stores several programs, documents, database etc. Whenever the results are saved, again they get stored in the secondary memory.

Secondary storage differs from primary storage in that it is not directly accessible by the CPU.

The secondary memory is slower than the primary memory. Some of the commonly used secondary memory devices are hard disk, CD etc.

Output Unit:

Ø Accepts results from the processing unit of computer.

Ø Converts those results into human readable form.

Ø Provides the results to outside world.

Central Processing Unit (CPU):

Ø  The part of the computer that executes the instructions (program) stored in memory.

Ø  The CPU is consists of the Control Unit (CU) and the Arithmetic/Logical Unit (ALU).

Ø  It is a brain of computer system.

Control Unit

The CU coordinates and controls all activities of the computer. It is the CU that tells the input unit to accept data from the outside world and pass it on to the storage for further processing.

The component of the CPU that control other components, So that the instructions are executed in the correct sequence.

Arithmetic/Logical Unit  (ALU)

The components of the CPU that performs arithmetic and logical operations it is called ALU.

Arithmetic Operations: These are the type of operations in which calculation(s) is /are involved.

Logical Operations: These are the type of operations in which decision(s) is/are involved.

Memory Unit: Internal data storage in a computer. The memory is comprised of a large number of individual cells, each with a unique number, known as its address, associated with it.