The first stage(1971-1973) is the era of the and microprocessorwhich we often called the first generation.The typical product are Intel4004 and Intel8008 microprocessors.The basic feature is the use of PMOS technologylow integration(4000 transistors) system architecture and instruction system are relatively simplemainly using simple machine language or assembly language.
The second stage(1974-1977) is the era of high-end microprocessorcommonly known as the second generationthe typical product i