The evolution of microprocessor was divided into four generations :
FIRST GENERATION :
The first microprocessor is intel 4004. PMOS microprocessor introduced in he year 1971 nt the intel corporation, USA. The enhanced version of this is intel 4040. Memory addressing capacity is 1kb, clock frequency is 750 khz. No of pins is 16 and clock freq is defined as the no instruction that can be executed in one sec.
eg. Rockwell international’s PPS-4, TOSHIBA t3472 etc.
SECOND GENERATION
The first 8 bit is microprocessor is intel 8008 introduced in the year 1972 which is a 8 bit pmosmicroprocessor .in the year 1973, intel 8080 which is an 8 bit, nmos microprocessor was in traduced which is faster and compatible to TTL than that of pmos technology. But intel 8080 requires three power supplies so in the year 1975 intel 8085 , an 8 bit nmos microprocessor was introduced which requires one power supply ie +5v dc. Memory addressing : -64 kb , clock frequency – 1mhz to 6mhz. No of pins 40.
eg. Rockwell international’s PPS 8, ZILOG’s z-800 etc.
THIRD GENERATION
In 1975, a 16 bit microprocessor was developed which is anhmos microprocessor. Memory addressing capacity: i mb to 16 mb, clock frequency 6 to 12.5 mhz, no of pins -40
eg. Intel 8088, 80186, 80286
Intel 80186 and 80188 are integrated microprocessors beside cpu. They contain some additional components that are PIC, DMA, PC Or timer, clock generator, peripheral chip select logic. Programmable state generator and local bus controller etc. In intel 80286 besides cpu it has integrated memory management unit, four level memory protections, it supports virtual memory and operating systems.
FOURTH GENERATION
After 1980, 32 bit microprocessors were produced. The first 32 bit microprocessor is iAPX 432. This is not popular as it is eventually disconnected. The most powerful and very popular 32 bit microprocessor is intel 80386. In short it is called intel-386. Memory addressing capacity 4gb, clock frequency-20 mhz to in ghz. No of pins is 132 or more.
eg. Pentium pro, Pentium II xenon, Pentium II celerum , Pentium III.
