The fourth generation computer refers to the computer made of large scale integrated circuits (LSI) and very large scale integrated circuits (VLSI) as the main electronic devices after 1970. For example, the 80386 microprocessor can integrate about 320,000 transistors on a chip with an area of about10mm × 10/0mm. ..

Another important branch of the fourth generation computer is the microprocessor and microcomputer developed on the basis of large-scale and ultra-large-scale integrated circuits.

Microcomputer has roughly gone through four stages:

The first stage is 197 1 ~ 1973, with 4004, 4040 and 8008 microprocessors. 197 1 year, Intel developed a MCS4 microcomputer (CPU 4040, four-bit computer). Later, MCS-8 with 8008 as the core was introduced.

The second stage is 1973 ~ 1977, which is the development and perfection stage of microcomputer. Microprocessors are 8080, 8085, M6800 and Z80. The original product is MCS-80 (CPU Intel (CPU is 8080, 8-bit computer). In the later period, there were TRS-80 (CPU is Z80) and APPLE-II (CPU is 6502), which was once popular all over the world in the early 1980s.

The third stage is 1978 ~ 1983. The development stages of 16-bit microcomputer are 8086, 808880 186, 80286, M68000 and Z8000. The representative product of microcomputer is IBM-PC(CPU is 8086). The peak products at this stage are Apple's Macintosh( 1984) and IBM's PC/AT 286 (1986).

The fourth stage is the development stage of 32-bit microcomputer from 1983. Microprocessors have successively introduced 80386 and 80486. 386 and 486 microcomputers are the original products. 1993, Intel introduced a microprocessor named Pentium or P5 (translated as "Pentium" in Chinese) with 64-bit internal data channels. Now Pentium III (also called P7) microprocessor has become the mainstream product, and Pentium IV is expected to be launched in June 2000.

Therefore, the performance of microcomputer mainly depends on the performance of its core equipment, the microprocessor (CPU).