The evolution history of CPU

The development of computers is mainly reflected in the development of its core component, the microprocessor. Whenever a new microprocessor appears, it will lead to the corresponding development of other components of the computer system, such as the further optimization of the computer architecture,

The memory access capacity continues to increase, the access speed continues to improve, peripheral devices continue to improve, and new devices continue to appear.

According to the word length and functions of microprocessors, their development can be divided into the following stages.

Stage 1 The first stage (1971-1973) is the era of 4-bit and 8-bit low-end microprocessors, usually called the first generation. Its typical products are Intel4004 and Intel8008 microprocessors and the MCS-composed of them respectively.

4 and MCS-8 microcomputers.

The basic characteristics are that it uses PMOS technology, low integration (4000 transistors/chip), relatively simple system structure and instruction system, mainly using machine language or simple assembly language, with a small number of instructions (more than 20 instructions), and basic instructions.

The period is 20~50μs, used for simple control situations.

Intel began developing the first microprocessor in 1969 as a project for Japanese computer manufacturer Busi, developing multiple chips for a series of programmable computers.

Finally, Intel launched the 4004 microprocessor to the global market on November 15, 1971. The Intel 4004 processor sold for $200 each that year.

The 4004 was Intel's first microprocessor, laying the foundation for future development of system intelligence functions and personal computers. It had approximately 2,300 transistors.

Stage 2 The second stage (1974-1977) is the era of 8-bit mid-to-high-end microprocessors, often called the second generation. Its typical products are Intel8080/8085, Motorola Company, Zilog Company's Z80, etc.

Their characteristics are that they use NMOS technology, which increases the integration level by about 4 times and the computing speed by about 10 to 15 times (basic instruction execution time is 1 to 2 μs).

The instruction system is relatively complete, with typical computer architecture and control functions such as interrupts and DMA.

In terms of software, in addition to assembly language, there are also high-level languages ??such as BASIC and FORTRAN and corresponding interpreters and compilers. In the later period, operating systems also appeared.

In 1974, Intel launched the 8080 processor as the computing core of the Altair personal computer. Altair was the destination of the Enterprise spacecraft in the "Star Trek" TV series.

Computer enthusiasts could buy an Altair kit for $395.

It sold tens of thousands of units within months, becoming the first model in history to be built to order.

The number of Intel 8080 transistors is approximately 6,000.

Stage 3 The third stage (1978-1984) is the era of 16-bit microprocessors, often called the third generation. Its typical products are Intel's 8086/8088, Motorola's M68000, Zilog's Z8000 and other microprocessors.

processor.

Its characteristic is that it uses HMOS technology, and its integration level (20,000~70,000 transistors/chip) and computing speed (basic instruction execution time is 0.5μs) are an order of magnitude higher than the second generation.

The instruction system is more abundant and complete, using multi-level interrupts, multiple addressing modes, segmented storage mechanisms, hardware multiplication and division components, and equipped with software systems.

Famous microcomputer products during this period include IBM's personal computer.

The personal computer launched by IBM in 1981 used the 8088 CPU.

Then in 1982, the extended personal computer IBM PC/XT was launched, which expanded the memory and added a hard disk drive.

The 80286 (also known as the 286) was Intel's first processor to be able to execute all the software exclusive to older processors. This software compatibility later became a registered trademark of Intel's entire line of microprocessors. During the 6-year sales period,

An estimated 15 million 286 personal computers are installed worldwide.

The number of transistors in the Intel 80286 processor is 134,000.

In 1984, IBM launched the IBM PC/AT, a 16-bit enhanced personal computer based on the 80286 processor.

Because IBM adopted a technology openness strategy when developing personal computers, personal computers became popular around the world.

Stage 4 Stage 4 (1985-1992) is the era of 32-bit microprocessors, also known as the 4th generation.