The Processor/CPU :- The CPU or central processing unit, the role of the CPU is to control and direct all the activities of the computer using both external and internal buses.It is a processor chip consisting of an array of millions of transistors.
Older CPUs are generally square, with transistors arranged in a Pin Grid Array(PGA).prior to 1981, chips were in ractangle size with two rows of 20 pins known as a Dual Inline Package.Most CPUs use either the PGA to the single Edge Contact Card(SECC) form factor.SECC is essentially a PGA-type socket on a special expansion card.