Why do we learn about 51 single-chip microcomputers?

Today I will tell you a secret. Why do we learn 51 single-chip microcomputers? Why do engineers, university teachers and college students in China like to use 51 single-chip microcomputers? The reasons are as follows:

1. Because the 51 core (referring to the single-chip microcomputer with 8051 CPU) has a lot of information and many types, it is popular among people, and it allows beginners to get twice the result with half the effort. Is it really like this? Maybe it was like this 20 years ago because there was nothing else to learn.

2. But this does not seem to be the case, because although there are many types of 51 single-chip microcomputers, and new products have integrated many more useful and simpler functions, people are still most fond of the 51 single-chip microcomputer with the least functions and the most complicated operation - AT89S51 single-chip microcomputer (ATMEL's early product).

3. Let's analyze the real reason why 51 single-chip microcomputers are widely used:

Before analyzing the reasons, let’s discuss a few issues

(1) When did the 51 single-chip microcomputer enter the market? Answer: The 51 single-chip microcomputer was developed in the 1970s and widely used in the 1980s.

(2) Were there other competing products at the same time? Answer: There was also Zliog's z80 microcontroller, but it withdrew from the market soon due to company strategy reasons (according to the Internet).

(3) Now let me ask you a question: How old are the people working on the front lines of education in companies and schools now? Answer: Around 40 years old.

(4) What were people in their 40s doing 20 years ago? Answer: They were in college, and the subject offered by the university was the 51 single-chip microcomputer.

(5) What did they do after graduation? Answer: Some went to work in companies, and they are now front-line engineers. Others stayed in school to teach, and they are now our beloved teachers working in the front line of education.

(6) What are they still using now? Answer: Most of them are still using 51 single-chip microcomputers. Engineers working in companies are still using 51 to do their own projects. Only when companies with fierce competition encounter projects that cannot be completed by 51 will they think about looking for a more powerful single-chip microcomputer, so some engineers will use other single-chip microcomputers. Teachers are different. The projects they do are not many, not big, and the competition is not fierce, so the 51 single-chip microcomputers they know are enough to cope with them. Therefore, their knowledge system has not been updated. Until today, they are teaching us, so that we are learning what they learned 20 years ago. This is the real reason why we are still learning 51 single-chip microcomputers.

Let's talk about the 51 microcontroller. Is it really easy to get started? Can you really get twice the result with half the effort? I personally think it's not the case, because many microcontrollers nowadays are easier to get started with than the 51 microcontroller. For example, the AVR microcontroller is easier to operate, has more on-chip peripherals, and the PIC microcontroller has a more streamlined instruction set with 33, 35, and 58 instructions (depending on the level of the microcontroller), which is a streamlined instruction set. The 51 series has 111 instructions, and the AVR microcontroller has 118 instructions.

This situation is slowly changing, because the 40-year-old workers are getting old, and we in our 20s are the masters of the future. At the age of 20, we have also learned more about microcontrollers, such as the 51-core: STC full series C8051F full series F1-core microcontroller: AVR PIC MSP430 and more advanced ARM-core microcontrollers, etc.

For those who like electronics and microcontrollers, I hope you can learn more about how to use them. [page]

The above is just my personal opinion.

Other well-known MCUs of the same period as the MCS51 core include Motorola's 6805 core, Zilog's Z8 core, NSC's Cop8 core, and the MCS48 core that was born earlier than the MCS51. There are also many less famous MCU cores. After 30 years, the eight-bit cores that are still in mass production and use are a bunch of up-and-coming ones, except for the HC08, the sister of the 6805. The reason for this is mainly that Intel opened up the 51-core license at that time. So far, many authorized and unauthorized suppliers have developed more than 10,000 51-core or 51-core compatible MCUs, and the 51 core is quite stable, and the instruction set is relatively reasonable. These are the reasons why generally skilled R&D chooses it. There are also many authorized production suppliers of ARM now. When ARM really has a stable core that has existed for a long time, this situation will definitely change.

The 8031 ​​chip in the early 51 core did not have the PROM that is essential for general MCUs, and users had to expand it externally. However, the Timer, I/O port, RAM, and Uart integrated on the chip are quite useful. An external address latch chip, a PROM, a clock source, and a DC power supply can adapt to many control tasks. It has many other advantages and is cheap, so it quickly became popular in China at that time.

It should also be pointed out that until the 1990s, most schools in China were still teaching Z80 or 8086, and teaching 51 was quite rare.

By the 1990s, the resources of the MCS-51 series (including chips, development tools, reference books, reference designs) were easily found in the domestic small and medium-sized markets, such as Z80, 6805, and Japanese NEC, etc. There were general distributors, but they only dealt with large factories and ignored small quantities of samples (this is probably related to the strategy of chip manufacturers).

But in the second half of the 1990s, the market began to diversify, with the emergence of PIC and AVR. By the beginning of this century, it was centered around ARM.

In any case, each one has its reason for existence. 4-bit MCU is still alive, and 8-bit will not die for the time being (at least, people in their 40s cannot see the possibility of its death).

MCS51 is knowledge that most people have experienced to some extent, but it does not mean that people around 40 years old only use MCS-51. We have seen many older people (around 50 years old) using AVR, PIC, and ARM.

While in school, I have received:

1) MCS-51 course (In the experiment, it is in assembly, and the conversion to machine code requires manual conversion by looking up a table, and then manually typing the hexadecimal value and pressing run to see the result)

2) Computer system structure course (the experiment was 8086 assembly, and the computer compiler was written, all conducted in DOS environment)

Teaching students is teaching them how to learn.

The 51 core is a miniature version of the 8086 bus structure, from the basic internal timer, interrupt, serial port to the external expansion of AD, DIA, RAM, and ROM.

Basically, if you know 51, avr, arm, and pic are no problem. But knowing pic and avr does not necessarily mean you know the others.

If students are only taught single-chip PIC and C8051F, most students may not know how to connect external RAM.