* Arithmetic logic unit(ALU) -:- the “ALU” performs the arithmetic and logical operations on the data as are result of execution of the decoding instruction multiplication compersio
           The control unit also control the operation of the “ALU”

* Register -:- the set of registers in a set of temprory memory location in the “CPU” and each register as are specific function.

     * Output -:- there devices are required to delever the result to the user of the computer  system some of the popular output as following.

i.e. (i) printer, (ii) speaker, (iii) projector, (iv) plooter modem of both output and input.

RAM(read only memory) -:- this is type of non-volatile, semi conducter, Random acess memory used for permanent storage it is a read only memory in the sense that the data is place in the “ROM” at the time fall it manufacture and can not be change their after.

*Part Of  Rom-:-
  1. PROM 
  2. EP2ROM
  3. EPROM
     *BITES AND BYTES -:- we measure the amount of memory in bites and bytes the word bites stanes for binary digit a bites always means either zero and one when we combind a such bites.

8 bites = 1 bytes
1024 byte = 1 MB
1024 MB = 1 GB
1024GB = 1TB

     *Cache memory -:-  it possible to build a fast memory but the cost puts the restriction on the sizes in the sense that large memory became very expensive the alternative is to introduce a small expensive but fast memory between the “CPU” and the main memory.