A COMPUTER IS COMPOSED OF FIVE PRINCIPAL

COMPONENTS:

1)CONTROL UNIT

2)MEMORY UNIT

3)ARITHMETIC-LOGICAL UNIT

4)CENTERAL PROCESSING UNIT

CONTROL UNIT:

The main function of the control unit is to fetch, interpret and control.

The execution of program instructions stored in the memory. An instruction specifies the operation and the operands (data) on which the operation is to be performed. The storage location, designed to temporarily hold instruction and information closely associated with the instruction, are called register and these have a very access retrieve.

MEMORY UNIT:

The computer memory is used to store both programs and data. It is also 

used for holding intermediate and final results of a computation.

A memory is just like a human brain. It is used to store data and instruction. Computer memory is the storage space in computer where data is to be processed 

and instruction required for processing are stored.

The memory is divided into large number of small parts. Each part is 

called cell. Each location or cell has a unique address, which varies from 

zero to memory size minus one.

Cache Memory

Cache memory is a very high speed semiconductor memory. Which can speed 

up CPU. It acts as a Buffer between CPU and main memory.

It is used to hold those parts of data and programs are transferred from disk to 

cache memory by operating system, from where CPU can access them.

ADVANTAGE

Cache memory is faster than main memory.

It consumes less access time as compared to main memory.

It stores the program that can be executed within a short period of time.

It stores data for temporary used.

DISADVANTAGE

Cache memory has limited capacity.

It is very expensive.

Definition of RAM

Random access memory (RAM) refers to a storage technology that allows you to read and write data as many times as needed. Contrast this to ROM which allows data to be written once after which it permits only reading.

RAM is typically erased when a computer is shut down, though some RAM devices are not limited to use working memory. In a board sense, modern storage devices for long-term or secondary storage, including magnetic media and laser-readable CDs and DVDs, are forms of random-access memory.

Definition ROM

Read-only memory (ROM) refers to a storage technology that allows you to write data only once. After the data has been written, you can read it an unlimited number of times. Contrast this with random –access memory (RAM) that allows you to read and write data as many times as needed.

Originally, the term ROM referred to memory chips. However, with the creation of other stored device, the term is being used more widely. In particular, CD-ROM is used to distinguish CDs that can only be read and not written too

ARITHMETIC & LOGICAL UNIT:

The function of A.L.U is to perform arithmetic operation on appropriate instruction and data and conduct comparison of stored of information so as to be able to make logical decision based on such comparisons. This unit contains the necessary components, such as adders, multipliers, counter, comparators etc.

INPUT & OUTPUT DEVICE

Input Device: Input Device is the units or the parts of the computer, 

which we (User) use to perform feeding data in computer (Inputting).

Some examples of Input Devices are key board, Mouse, Light pen 

and scanner.

Output Device: Which parts computer functions use to produce 

output result as per given instruction are called output device. Some examples 

of output devices are printer, monitor, and sound system.

The combination of Input and Output Device are called I/O Device.

CENTERAL PROCESSING UNIT:

The CPU (central processing unit) is the part of a computer control the interpretation and execution of instructions. Generally, the CPU is a single 

microchip, but that doesn’t necessarily have to be the case. In the consumer 

desktop and laptop market, the CPU market is dominated by Intel, AMD, and 

IBM. These manufacturers supply the computer markets such as Dell, HP, and 

Apple.

Due to its importance to every computing task, the speed of the CPU, 

usually measured in gigahertz (GHz) is the number that most vendors use in 

their marketing. in the past, the larger the number, the faster the computer could be expected to be. However, In recent years, the speed of the CPU has had less 

impact as other components of a computer take on more and of the workload. 

Also, differences in technology mean that a slower chip that performs more calculations per cycle can actually be faster than a higher rate chip doing 

fewer calculations per cycle