What are the five major parts of the internal hardware structure of 805 1 single chip microcomputer?

805 1 MCU is the CPU of PC, based on the architecture of von Neumann.

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Basic structure

5 1 MCU was originally developed and designed by Intel, but later Intel sold the design scheme of 5 1 core to several large electronic design manufacturers, such as SST, Philip, Atmel and other big companies. If there are all kinds of single-chip computers with 5 1 as the core, Intel's own single-chip computers will be inferior. The single-chip computers introduced by these major electronic manufacturers are all compatible with the 5 1 instruction, which extends some functions on the basis of 5 1, while the internal structure is consistent with 5 1.

Structural frame

The CPU of PC is based on von Neumann architecture, but both MCU and Dsp are based on Harvard architecture. Harvard architecture is very different from von Neumann architecture. Under the Von Neumann architecture, there is only one address space, and ROM and RAM can be randomly arranged in different spaces within this address range, that is, ROM and RAM addresses are uniformly allocated. When CPU accesses memory, an address corresponds to a unique storage unit, which can be ROM or RAM. However, under the Harvard structure, ROM and RAM are addressed separately, that is, programs and data are stored separately, and they can be accessed at the same time with different instructions. Under such an architecture, it is beneficial to improve the execution speed of instructions. In the next chapter, we will introduce the memory configuration of single chip microcomputer in detail.

(1) An 8-bit microprocessor (CPU).

(2) On-chip data memory RAM( 128B/256B) is used to store readable and writable data, such as intermediate results and final results of operations, and data to be displayed. SST89 series single chip microcomputer can provide 1K RAM at most.

(3) On-chip program memory ROM/EPROM(4KB/8KB) is used to store programs, some original data and tables. But there are also some single-chip computers without ROM/EPROM, such as 803 1, 8032, 80C3 1 and so on. At present, the development trend of single chip microcomputer is to integrate both RAM and ROM into single chip microcomputer, which not only facilitates the design of users, but also improves the anti-interference of the system. The 89-series single-chip microcomputer introduced by SST company integrates 16K, 32K and 64K flash memories respectively. Users can choose according to their needs, and readers can check the back part of the book.

(4) Four 8-bit parallel I/O interfaces P0~P3, each of which can be used as input or output.

(5) Two timers/counters, each of which can be set in counting mode to count external events or timing mode, and can be controlled by the computer according to the counting or timing results. In order to facilitate the design of serial communication, the current 52-series single chip microcomputer will provide three 16-bit timers/counters.

(6) Interrupt control system with five interrupt sources. Now the newly introduced single-chip microcomputer has more than five interrupt sources. For example, SST89E58RD has nine interrupt sources.

(7) The serial I/O port of full-duplex UART is used to realize serial communication between single-chip computers or between single-chip computers and microcomputers.

(8) On-chip oscillator and clock generation circuit, but the timing crystal and trimming capacitor need external connection. The maximum allowable oscillation frequency is 12MHz. The maximum allowable oscillation frequency of SST89V58RD is 40MHz, which greatly improves the execution speed of instructions.

The above components are connected with each other through an internal data bus.

The internal structure of 805 1 single chip microcomputer is shown in Figure 2-2. A complete computer should be composed of arithmetic unit, controller, memory (ROM and RAM), data bus and I/O interface. A general microprocessor (such as 8086) only includes an arithmetic unit and a controller. Compared with the general microprocessor, 805 1 has four 8-bit I/O ports, a serial port, 4KB ROM, 128BRAM, and many working registers and special function registers (SFR), so the single chip microcomputer has more powerful control functions than the microprocessor. Single-chip microcomputer is specially designed for control, while ordinary microprocessor is used for calculation function. The following figure describes the functions of each part.