8051 Microcontroller

A microcontroller is one such basic computer. Oftentimes microcontrollers are used to run processes in electronics and machinery that do not change over time, and require no interfacing with users whatsoever. For instance, many of the processes in a car’s engine are controlled by microcontroller computers. The same goes for many power tools and other home electronics. Unlike a desktop computer, these microcontrollers are not easily reprogrammed or repurposed by users. Their purposes are fixed, and relatively limited. However, they are similar to desktop computers in that they contain memory chips, processor chips, and do send and receive signals from other connected parts of whatever device they’re installed in.

Microcontrollers, which are also known as “processors” or “microprocessors,” are found in all sorts of electronic devices. Office appliances, microwaves and toaster ovens, pacemakers, children’s toys and video games, cars and trucks, and power tools all are designed with microcontrollers that govern their internal functions. When the “on” switch in any of these devices is pressed, it is the microcontroller that directs the device how to process that input. When any of the settings on a microwave or rotary saw are set by the user, their microcontrollers interpret the new settings and adjust the devices’ operations accordingly.

Microcontrollers are found in both analog and digital devices, but when a device is digital, that virtually guarantees that a microcontroller can be found somewhere within it. Microcontrollers have been around for decades now, and have gotten continuously smaller. As they decrease in size and in manufacturing costs, the number of devices that can be made digital has correspondingly grown. Additionally, microcontrollers can be made so simple that they consume almost no power when a device isn’t operating, and very, very little when it is. This makes it feasible to run microcontrollers off of battery power without quickly draining the battery to the point it needs recharging.

The 8051 Microcontroller

One of the most famous microcontrollers ever manufactured was the Intel MCS-51, known more commonly as just the “8051.” The 8051 microcontroller is a very simple computer, of the sort referenced above. It has no monitor, no buttons, and could fit easily in the palm of someone’s hand. There were many iterations of the 8051 over the years, and while none of them looked exactly the same, most of them looked very similar. They were just black plastic casings, either rectangular or square shaped, with metal input and output rods extending out from them. These rods would be used to connect the 8051 to the substrate of a motherboard, or wherever else the microcontroller might be installed within an appliance. Inside the black case were the inner workings of the 8051: random access memory, read only memory, and a central processing unit. These, of course, are the essential components of any computer. Yes, the little black chip known as the 8051 was, at a fundamental level, little different from the high-tech laptops and desktops and tablets people use today.

What Are The Features Of The 8051 Microcontroller?

The 8051 comes pre-installed with a variety of different features and functions. The guts, or inner parts, of the 8051 are listed below.

16-bit Counters

Counters are important for all sorts of programming tasks that require something to happen after a set period of time. The 8051 had two counters (sometimes called “timers”) inside of it, which allowed for it to control tasks that were time dependent in one way or another.

One Serial Port

Serial ports are a way of connecting computer components to each other. The eight- and nine-pin ports that many computers used to have (and some still do) were examples of serial ports. The 8051 had a much smaller version that allowed it to plug into other devices or computer chips within a device.

An Input/Output Port

Similar to the serial port in its purpose, this also functioned to allow the 8051 to send information to, and receive information from , other parts of whatever device it was installed in.


ROM, which stands for read-only memory, is not editable, or can be edited only with great difficulty. For that reason, it is used to store information that will be valid for the life of the device. Permanent instructions could be included in the ROM portion of the 8051. The most basic parts of the microcontroller’s programming would be stored in this portion of the memory.


RAM, or random access memory, has the advantage of being writeable, erasable, and rewriteable on the fly. No matter where a bit of information is written on the memory, it can be access quickly. This allows devices to write on the RAM fast, without ordering the information, and then call it up equally fast and no matter where on the disk the data was placed.

An Address Bus

An address bus provides directions to a piece of information stored in either read-only memory or random access memory. The address bus assigns each piece of data a unique address, and then recalls and provides the address when the data is needed.

A Data Bus

A data bus provides directions between the components of the microcontroller. In effect, it tells the components where and how to communicate with each other.

A Logic Unit

There are numerous logical operations embedded in computer programming. The logic unit processes these and directs the computer how to proceed.

The Development of The 8051

The 8051 was created in 1980 by Intel. During the early 1970s, a team of engineers working for Intel had invented the world’s first microprocessor, a chip that was intended to run a calculator that would be sold in Japan. (Texas Instruments, another calculator company, developed a microprocessor concurrently and independently, so TI and Intel share credit for having the world’s first microprocessors.)

The microprocessor developed by Intel grew out of an early processor technology known as the “ASIC,” or application-specific integrated circuit. ASICs are in many regards similar to microprocessors: they look similar, they are often customized to direct just one task, and they are run by a series of gates (or transistors) embedded within the chip. But the microprocessor developed by Intel was a more complicated and more advanced device than the ASIC that was en vogue at the time. (Like the microprocessor, the ASIC has evolved greatly since the 1980s, and is still in use today.) The design of the microprocessor allowed for faster access to memory and control over a greater range of processes than the ASIC was capable of. The microprocessor, once invented, would quickly push forward the number and range of tasks that a device could be programmed to do. The calculator, once it switched from ASICs to microprocessors, became a far more nimble and capable device, but that was only the first of many advances for which the microprocessor has been responsible.

Over time, Intel’s microprocessor offerings grew. The field was crowded with competing companies, and advances on the academic side of computer science were quickly pushing forward the technology and logic behind microprocessors. By the time the 8051 was released in 1980, it was substantially more powerful and more capable than the original microprocessors put out by Intel almost ten years prior. Intel continued manufacturing the 8051 throughout the 1980s and into the 1990s, but eventually stopped production and development of the chips. However, the 8051 remains in wide use, because a number of other firms stepped in when Intel exited the 8051 market, and they began producing similar chips that still bear the “8051” designation. Today, the descendants of the original 8051 are mostly found in battery powered electronic equipment, on account of the 8051’s low power requirements and near-zero offload power demands.

What Is The Memory Architecture Of The 8051 Microcontroller?

Within the 8051, the memory is divided into four separate parts. This division and design is referred to by engineers and computer scientists as the “memory architecture.” The four parts of the 8051’s architecture are as follows: the internal RAM, the program memory, the external data memory, and the special functions register.

The first section of architecture is devoted to the internal RAM. After that, the special functions registers are placed second within the chip’s memory architecture.

Third in the architecture is the program memory, which is written within the chip’s read-only section. Program memory contains all the basic pieces of code needed for the operation of the 8051 chip and the operation of whatever device the chip is integrated into. The most essential data, consequently, is stored within this portion of the memory architecture.

Fourth is external data memory. External data memory is random-access memory also. Sometimes this memory is in fact stored externally, but not always. The “external” in its name refers to the process by which the 8051 calls on the data stored in this section, not to the actual location of the data.

What Applications Run On The 8051?

As noted above, the 8051 is no longer a part of Intel’s product line, but chips similar to it or, in some cases, almost identical to the 8051 developed and sold by Intel, are still widely used in today’s electronics. The coding that can be done on the device has gotten far more advanced over the years, and its speed has increased substantially too, such that the 8051 can now control devices that are vastly more complicated than the calculators it was originally built for back in 1980. Today, the 8051 is the microprocessor behind numerous USB pen drives, major household appliances, broadcast and communications equipment, and power tools. The 8051 can be programmed to run any and all of these devices. It’s very likely that, even as the rest of the technology world advances, the 8051 will still be used in consumer and industrial electronics, in one form or another, for years to come. The framework that Intel developed for the 8051 has proven very flexible, and it’s probable that programmers and engineers will continue to improve on it long into the future.

Who Makes 8051 Controllers Now?

Analog Devices is a semiconductor and microprocessor company based in Massachusetts. Founded in the 1970s, Analog Devices has a wide range of products that include the 8051, other forms of microprocessors and integrated circuitry, as well as semiconductors and other building blocks of modern electronics.

Atmel is an American company specializing the manufacture of microprocessors and other component parts of computers. Atmel is based in southern California.

Infineon is a large, multinational company with headquarters in California, Singapore, and Tokyo. They develop chips for automobiles and industrial applications, and use the basic 8051 framework for many of their products even today.

Maxim Technologies is a somewhat smaller manufacturer of the 8051 chip. Maxim is based in Ohio.

Microchip makes 8051 microcontrollers and many other types of chips and microprocessors as well. The company has a long history in the field and has sold more than one billion chips in its time. Microchip has its headquarters in Arizona.

Silicon Labs is a large, publicly traded company headquartered in Austin, Texas. The 8051 is among their extensive line of microcontrollers and other processing chips. Silicon Labs’ products find their way into stereo equipment, video projectors and TVs, and scientific equipment as well.

STMicroelectronics is very large technology manufacturer that specializes in semiconductors, but also produces products like the 8051. STMicroelectronics is based in France.

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