Why is the processor called 8086 and so on? How did you get here? 20

The processor 8088 CPU is a quasi-sixteen-bit, successor to the 8086, and was chosen as the CPU by the world's best-selling IBM PCs, which has a similar architecture to the 8086 CPU. The executor of the two CPUs is exactly the same, and their instruction system, addressing capability and programming method are the same, so the two CPUs are fully compatible. The main differences between these two types of CPUs can be summarized in the following aspects:

1 Difference in the number of bits on the external data bus: The external data bus of the 8086 CPU has 16 bits, and one word (16-bit data) can be input and output in a bus cycle, so that the speed of the system to process data and respond to interruptions can be accelerated; The 8088 CPU's external data bus is 8 bits, and only one byte can be input and output (8-bit data) in a bus cycle. Because of this, the 8088 is known as a quasi-16-bit processor.

2. Difference in instruction queue capacity: The instruction queue of 8086CPU can accommodate 6 bytes, and 2 bytes of instruction ** are taken out from memory in each bus cycle to fill in the instruction queue, which can improve the parallelism rate of finger fetching operations and other operations, thereby improving the working speed of the system; The instruction queue of the 8088CPU can only hold 4 bytes, and only one byte of instruction can be fetched in each bus cycle**, which increases the time for bus fetching instructions, and may affect the parallelism rate of fetching instructions and other operations under certain conditions.

3 Differences in pin characteristics: The pin function of the two CPUs is the same, but there are the following differences:

1) AD15 AD0 is defined differently: in 8086 it is defined as an address data multiplexing bus; In 8088, since only 8 data buses are used, the 8 pins corresponding to AD15 AD8 of 8086 are only used as address lines.

2) Pin 34 is defined differently: defined as BHE signal in 8086; Whereas, in 8088 it is defined as ss0, which is used together with dt r, io m as a periodic state signal in the smallest mode.

3) Pin 28 has a different phase: M io in 8086; In the 8088, it was inverted and changed to IO M for compatibility with the bus structure of the 8080 8085 system.

In 1979, Intel introduced the 8088 chip, which was still a 16-bit microprocessor with 29,000 transistors, a clock frequency, a 20-bit address bus, and 1MB of memory. The 8088 internal data bus is 16 bits, the external data bus is 8 bits, and its sibling 8086 is 16 bits. In 1981, the 8088 chip was first used in IBM PC, creating a new era of microcomputers.

It was also from 8088 that the concept of the PC (personal computer) began to develop around the world.

In 1982, when many young readers were still in their infancy, INTE had launched the epoch-making latest product, the 80286 chip, which was a leap forward from the 8006 and 8088, although it was still a 16-bit structure, but it contained 10,000 transistors inside the CPU, and the clock frequency was gradually increased from the initial 6MHz to 20MHz. It has a 16-bit internal and external data bus, a 24-bit address bus, and addressable 16MB memory. Starting with 80286, the way CPUs work has evolved into two ways:

Real mode and protection mode.

32-bit.

(1) The queue length of 8088 instructions is 4 bytes, and 8086 is 6 bytes.

2) The data bus width of the 8088 is 8 bits in the BIU and 16 bits in the EU, so it takes two read and write cycles to complete the 16-bit memory read and write operation. The 8086 has both BIU and intra-EU data bus widths.

It's 16 bits.

3) The 8088 external data bus has only 8 AD7 AD0s, that is, the internal is 16 bits, and the external is 8 bits, so 8088 is also called a quasi-16-bit machine.

**The CPU is one of the main equipment of the computer and the core accessories in the computer. Its function is mainly to interpret computer instructions and process data in computer software.

The CPU is responsible for reading the instructions, decoding the instructions, and executing the core components of the instructions.

8086 is 16 bits, 8088 is 8 bits, they are all antique products of Intel, and the development order is roughly like this:

8086, 8088, 286, 386, 486, 586 (Pentium), Ben 2, Ben 3, Ben 4, Ben D, Core.

（1）8088

The instruction queue length is 4

bytes, 8086

It's 6 bytes.

The width of the data bus within the BIU is 8

bits, while the data bus width within the EU is 16

bits, so to 16

A memory read and write operation of bits takes two read and write cycles to complete. BIU of 8086

and data bus widths within the EU. It's 16 bits.

There are only 8 external data buses

bar ad7 ad0, i.e. inside is 16

bits, external is 8

bits, hence 8088

Also known as a quasi-16-bit machine.

8086 8088 microprocessor.

The 8086 is a 16-bit microprocessor of the Inter series with 10,000 transistors on the chip and HMOS.

Manufactured with a single +5V power supply and clocked at 5MHz to 10MHz.

The 8086 has 16 data lines and 20 address lines, and it can handle both 16-bit and 8-bit data. Can.

The addressing memory space is 1MB

At the same time as the launch of the 8086, Inter also launched a quasi-16-bit microprocessor 8088, 8088 internal registers, the arithmetic components and the internal data bus are designed according to 16 bits, and there are only 8 external data buses alone. The main purpose of the introduction of the 8086 was to be directly compatible with the existing set of inter peripheral device interface chips at that time. The 8086 and 8088 are identical or slightly different in terms of register structure, programming structure, memory organization, and I-O port organization, which are explained in this section.

CPU, a 16-bit processor from Intel. It should be the previous generation of 80286, and from 286, it is 32 bits.

2. The current PC processors are all backward compatible until 8086, which is collectively referred to as 80x86. Therefore, in the assembly textbook, the 8086 CPU is talked about, and the term "80x86 instruction set" is often mentioned in assembly language, which means that the instruction set compatible with these CPUs.

3. Let's learn about the characteristics.