14 – Computer Architecture

This chapter provides an overview of computer architecture. The development of affordable computers happened when the Japanese company, Busicon, commissioned a small, at the time, company named Intel to produce a set of eight to twelve ICs for a calculator. Instead of designing a complete set of ICs, Intel produced a set of ICs which could be programmed to perform different tasks. These were the first ever microprocessors. This chapter briefly explains the Intel microprocessors, as it is the first microprocessor, named the 4004, and it 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 just four bits of data at a time (a nibble), contained 2,000 transistors, operated with 46 instructions and allowed 4 KB of program code and 1 KB of data. The second generation of Intel microprocessors began in 1974 with the 8-bit processors; these were named the 8008, 8080 and the 8085. Thereafter, the chapter also describes registers.