Computer Busses

A

PC Processors

A.1 Introduction

Intel marketed the first microprocessor, named the 4004. This device caused a revolution in the electronics industry because previous electronic systems had a fixed functionality. With this processor the functionality could be programmed by software. It could handle four bits of data at a time (a nibble), contained 2000 transistors, had 46 instructions and allowed 4 KB of program code and 1 KB of data. The PC has since evolved using Intel microprocessors (Intel is a contraction of Integrated Electronics).

The second generation of Intel microprocessors began in 1974. These could handle 8 bits (a byte) of data at a time and were named the 8008, 8080 and the 8085. They were much more powerful than the previous 4-bit ...