Evolution of Microprocessors

In the last fifty years, semiconductor technology has rapidly evolved. Starting with transistors and integrated circuits (ICs) in the 1950s, advancements led to small scale integration (SSI), medium scale integration (MSI), and large-scale integration (LSI). Today, we have very-large scale integration (VLSI) and super large-scale integration (SLSI). Microprocessors, from the Intel 4004 to 32-bit CPUs, have revolutionized computing and control applications. Microprocessor are classified into four generations which are discussed in subtopics below 

First generation 

The first microprocessor, the Intel 4004, was introduced in 1971 by scientist Fagin for use in calculators and was not suitable for general computing. In 1972, Intel released the 8008, the first 8-bit microprocessor, featuring 45 instructions and using LSI technology. Ex: INTEL 4040, Toshiba's T 3472 

Second generation 

In 1976, the 8085, an 8-bit microprocessor, was introduced. Microprocessor development aimed to integrate a complete microcomputer system, including CPU, ROM, RAM, clock, and I/O ports, into a single package. Ex: Intel 8048, motorala MC 6801 etc. 

Third generation 

Another key direction in microprocessor evolution has been creating processors that function like minicomputers, handling bytes, character strings, and instruction cycles of 1 microsecond. In 1978, Intel introduced the high-performance 16-bit microprocessor, the 8086 (APX 86), developed by Stephen Mors and Druce Revenal. Ex.: INTEL 8086, 8088, zylog z8000, M 6800 etc. 

Fourth generation 

In 1981, Intel introduced the 32-bit 80386 microprocessor, capable of addressing 4 gigabytes of physical memory. Examples include M68020, HP32, and iAPX432. Recently, Intel released Pentium I, II, III, IV, Core 2 Duo, and Xeon, the most advanced microprocessors