8051 FAMILY MICROCONTROLLER PROCESSOR ARCHITECTURE BASIC INFORMATION

THE 8051 FAMILY MICROCONTROLLER PROCESSOR ARCHITECTURE

You might wonder why the 8051 family of processors was chosen for this purpose, as it is a relatively old processor. If you read current technical journal articles, you might get the impression that all the action is in 32-bit micros.

That is primarily due to the fact that the companies that sell the high-end devices are working very hard to put their newest technology in front of their\ customers, and they are the ones who write most of the trade articles.


It is important to note that the trade press is always emphasizing the high end 16-bit, 32-bit, and larger processors due to their dependence on the advertising revenue from chip vendors. Though you would never guess it from reading these publications, it is only recently that shipments of 8-bit microcontrollers have exceeded 4-bit units.

It will be quite some time before the 16-bit micros will approach the sales volume the 8-bit units have  reached, and the 8-bit units are still growing in volume. According to one of the leading industry publications, there are more 8051 derivative CPU chips being produced than any other 8-bit micro.

Once you have learned the concepts of the 8051, you will find that the next architecture you need to use will be much easier to learn.

The 8051 microcontroller has the following characteristic:

• Interfacing to the processor’s multiplexed address/data bus provides valuable design experience.
• Development tools, including assemblers, simulators and compilers are readily available as freeware shareware and demo versions.
• It is available at a low cost, allowing low cost versions of in-circuit emulators, peripheral components, and single board computers to be purchased by the student.
• The 8051 is the most popular microcontroller family, with many derivatives available, and multiple vendors manufacture it.
• The 8051 architecture is available in a wide range of cost, size, and performance. For example, one version is available in a 20-pin small outline surface mount package for less than a dollar in volume, and another one is about eight to ten times the speed of the original 8051.
• The 8051 CPU is also available as a building block for custom chip designs, and is the most popular CPU for “system on a chip” designs. It is also the only readily available, non-proprietary building block CPU architecture available for chip design.

Software tools for the 8051 family, such as assemblers, compilers and simulators are available at no cost on the internet. Hardware tools, such as the combination software development kit and in-circuit emulator, are available for under $100, and complete design documentation is available on the web to allow anyone to build their own.

In addition, the 8051 has the simplest timing specifications of a device which can address external memory, making it practical to go into the details of the design which are necessary to understand.

With less than two dozen timing specifications (compared to several times as many for most other equivalent processors), it is possible to cover the timing specifications in detail.

Once this process is understood, it is a straightforward jump to understanding and using the larger number of equivalent specifications characteristic of other devices.