Intel 8051. 30 years in devices, devices and soft toys

What do vending machines, traffic lights and a talking teddy bear have in common? The question is probably not the easiest, so we will not be bothered: they are all controlled using an Intel 8051 microcontroller - perhaps the most popular controller for embedded systems in their entire history. And although back in 1996, the 8051 was replaced by Intel with a more advanced model, its clones still continue to be produced by a dozen companies. It seems that such an unusual long-liver is worthy of at least a small post.


I would like to immediately make a reservation. It is more correct to speak about the mega successful family of Intel MCS-51 controllers, consisting of 13 representatives: 8031, 8051, 80C31,80C51, 8032, 8052, 80C32, 80C52, 8751, 8752, 87C51, 80C152, 8XC51FA. However, 8051 stands alone in it - it was this model that became breakthrough, therefore in the future we will consider the entire series as a whole, and 8051 as an example.
Intel 8051 replaced its predecessor 8048 in 1980. The reason for its success was a combination of healthy conservatism and technological innovations, so necessary at that time and almost immediately picked up by the market. All these innovations somehow related to performance. The basic structure of the 8-bit arithmetic logic unit was preserved, however, a huge number of bit-oriented operations were introduced; the number of transfer teams without battery involvement has increased, multiplication, division commands and new subtraction commands have been added. There are improvements when working with the stack.


Intel 8051 controller
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Changes in the structure of the time cycle of the microcontroller led to a significant acceleration of work with external memory programs and data. The address space of the internal program memory has been expanded and the external memory space of programs and data has been increased to 64 KB. The 16-bit registers of the instruction counter and the data pointer allowed us to directly access the entire range of addresses, which made it possible to implement fast processing of large data arrays. All software-accessible microcontroller nodes are summarized in a special area of ​​data memory, which made it possible to access them as normal cells of the resident RAM. While maintaining the consumption of crystals was significantly increased the maximum clock frequency of the microcontroller to 12-16 MHz.


Generalized block diagram of the controller Intel 8051

The Intel 8051 controller consists of the following main components:

• 8-bit CPU (1-byte ALU and hardware implementation of multiplication and division);
• ROM programs with a capacity of 4 KB;
• 128 bytes data RAM;
• 32 duplex programmable interface lines;
• two 16-bit timers for counting external events and clocking the communication port;
• asynchronous duplex serial I / O channel with speed up to 375 kbps.

The Intel 8051 was the first embedded controller to learn how to receive and transmit data simultaneously, which also predetermined its success. Now the MCS-51 has enough power to use, say, in cable television boxes (there they are responsible for synchronization, audio decoding and OSD). Another important step forward was the transition to CMOS production technology, which opened for the MCS-51 the world of portable technology, and not only devices and devices, but also, as already mentioned, wonderful and extremely progressive at that time children's toys, such as Talking Wrinkles. (controller 8031, 1986).


Promotional Video Toys Talking Wrinkles

In 1990, Intel celebrated a kind of anniversary - 100 million MCS-51 controllers released. This was truly the heyday of the series, the controllers then appeared at unbelievable speed - 1 piece in 0.7 seconds! And each piece was used: in the onboard systems of leading manufacturers, such as Ford, General Motors, Saab, Volkswagen and BMW; in flight recorders and thousands of other important and necessary devices. Not surprisingly, the next 100 million were produced in just a few years. Now, of course, the pace is not the same, but interest in the MCS-51 is still continuing. There is only one example. In 2012, a new textbook on Intel 8051 and programming for it was released in Russian. Just from this textbook, we kindly borrowed some of the information and the scheme for the post.