The display-

through thedisplay element the computer sends out information, such as results of any calculation ,it has carried out according to some program .The display element can be of a wide variety of types:seven segment display wid each segment made of LEDs or LCD segments and finally the CRT display which enables display a lot of information in one group.

the display interface-

Display interface is necessary for taking information from the computer operation controller and making it available to the display device in appropriate format .The display interface can be met bt ICs specially designed for such purposes.

ROM-

it is a permanent memory area in which the programs once stored are not altered when the power to the computer is turned OFF and also cant be overwritten.For a blank ROM,the manufacturer supplies the device without any information in it,information can be entered electrically into the memory space which is called the burning of ROM.

RAM-

besides ROM area, every computer has some memory space for temporary storage of data as well as for programs under development. The memory devices used for this purpose are called RAMs or Read-Write Memory.The contents of the RAM memory are not permanent and are altered when the power is turned off. RAM memory contents are not retained when power goes off ,the RAM memory is considered to be volatile memory. When alternate power such as in the form of a battery is provided the RAM is then said to have a battery back-up.

CPU-

It co-ordinates all operations of a microcomputer . It feches programs stored in the ROMs or RAMs and executes the instructions depending on a specific instruction set,which is the characteristic of each type of CPU and which is recognised by the CPU. The signals associated with the CPU are address lines , data lines ,read lines , write lines , control lines , interrupt signals etc.