Embedded system

An embedded system is a computer system that is designed to perform specific tasks and is completely enclosed in the device it is operating. Some examples include bank automated teller machines (ATMs), calculators, digital cameras, printers, programmable thermostats, video games, antilock brake systems in cars, and computerized toys. Unlike the system in a desktop or laptop computer, an embedded system generally has no peripheral devices such as separate screens, keyboards, etc. This definition is being stretched at times as some embedded system devices, such as cell phones, electronic tablets, and other handheld computer devices, become expandable. However, the way these systems are designed keeps them within the realm of embedded systems.

Background

The earliest recognized embedded system is generally considered the small computer used to control the guidance system on the Apollo mission rockets in the 1960s. Designed at the Massachusetts Institute of Technology (MIT) and known as Luminary, the seventy-pound computer was operated by simple word pairs (noun-verb). It controlled the flight of the spacecraft, especially during the critical phase when the ship and its human passengers were re-entering Earth's atmosphere. Despite the importance of the task, this computer was less sophisticated than many twenty-first-century computerized kitchen appliances. Luminary was considered an embedded system because it was essentially self-contained and designed for a single purpose.

The space program and the military continued to use embedded systems for rocket guidance in the 1960s. Other devices, such as cameras and video games, followed over the next decade. The first Intel processor became available in 1971, further expanding the range of embedded systems. The 1970s also saw the earliest cell phones, although it would take a full decade before consumer cell phones were on the market. By the 1980s, embedded systems were increasingly added to existing products such as cars, some appliances, toys, and other devices.

Overview

Embedded systems are microprocessors that are used in devices other than standard desktop, workstation, and laptop computers used in homes and offices. The term refers to microprocessors intended to perform a specific, limited function in a device with a primary function other than those done by traditional computers. They are commonly found in small computer-like devices such as tablets and portable games; communications devices such as cell phones; equipment that processes audio and video data such as cameras, toys, and video recording devices; and components that control other devices such as appliances, vehicles, and military applications.

Besides the uses, embedded systems differ from the microprocessors in traditional computers in several other ways, although not every device will have all of these characteristics. Their focused use means that embedded systems generally need less memory and fewer ways for a person to interact with them. Because of this, the equipment is usually smaller, less expensive, and uses less power than the microprocessors in a full-sized computer.

However, there are often demands placed on embedded systems that are not present in most traditional systems. For instance, it is usually very important that the embedded system respond consistently with a reliable response time. Often, the system must respond in real time, performing the assigned function almost as quickly as a human reflex reaction. Failure of these systems can be more critical than failure in a desktop computer; while a desktop computer failure might result in the loss of time and money, the failure of an embedded system controlling the brakes in a car can result in a fatal accident.

While the microprocessors used in computers are generally very similar, the vast number of uses for embedded systems means that the microprocessors used in them are built to many different parameters. These specifications for their design, or architecture, can vary greatly, but there are some similarities. They are generally designed to include at least one microprocessor that serves as the brain of the system. The embedded system also usually includes one or more microcontrollers with all the memory the device needs. Their specialized nature means that the entire embedded system can often use a program known as a single assembly program instead of a larger, more involved operating system. In some cases, however, an operating system is used. This may be custom-made for the operation or adapted from a larger system. Embedded system devices manufactured in the United States and Europe that use an operating system often use a Linux-based system, while Japanese-built systems often use an operating system known as TRON.

Each embedded system is specially designed to meet the needs of the product it is intended to control. The systems require varying levels of reliability and safety. While a certain level of reliability will always be expected in any product, those intended to run a major appliance will need a higher level of reliability than one intended to run a toy, for instance, while the component in the toy might need to be designed to be encased so it is less accessible and safer for a child. The systems also need to be designed to interact with other systems; a thermostat will need to be able to activate the heating system, for example, while the computer controlling a coffee maker will need to interact with the mechanical parts of the system that release the water.

As a result of the many and varied uses for embedded systems, there are many more designs for them than there are for the microprocessors used in traditional computers. There are also many more microprocessors used for embedded systems than for traditional computers. It is estimated that while millions of microprocessors are used in traditional computers each year, billions of them are used in embedded systems.

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