The processor or CPU (Central Processing Unit) indicates PC’s computing power. It controls and directs all processes in PC. It contains millions of transistors and its speed is measured by its clock speed in MHz or GHz (1 megahertz = 106 cycles and 1Gigahertz = 109 cycles per second).
First IBM PC CPU, the 8088, ran at 4.77 MHz, today’s PCs exceed 1 GHz. CPU die is a small block of semi conducting material, on which a circuit is fabricated. Most processors have an internal cache which stores frequently used data and instructions. Cache is broken up into two classifications, L1 which is the internal cache and L2 which is the external cache. Each processor has buses to transmit data with rest of computer components. There are two types of bus used
- The data bus is used to send and receive data.
- The address bus is used to describe memory address locations.
The following tables summarize some CPU and their characteristics
|CPU||Data Bus (bits)||Address Bus (bits)||Speed (MHz)||Transistors|