It is the brain of the computer.it has two main parts:the control unit and the arithmetic and logicunit(Alu).The design of the CPU affects the processing capacity and the speed of the computer,as well as the amount of main memory it can use effectivel.
We usually divide the storage devices into two types: the main memory and the secondary storage.the main memoy called a read-only memory(ROM).ROM can be read,but not be written.