Embedded systems are purpose built computer systems for one specific task that form part of larger electrical or electro-mechanical machines. More often than not, today's embedded systems are based on microcontrollers but ordinary microprocessors with added hardware are also common.
The history of embedded systems really began with the inception of digital electronic computers themselves and the few first ever digital computers in the late 1930s and early 1940's. Initially fuelled by its potential use in military applications and later for its utility in an countless fields of study, computer science continued advancing faster and faster after more universities and corporations were interested in the subject . Before 1960, less than 20 years after the first fully functional "modern computer", the Colossus, was built, several programming languages, compilers, and key technologies like the magnetic core memory and the transistor and the integrated circuit already existed. Between 1962 and 1972 Texas Instruments introduced the 7400 series of logic integrated circuits, the programmable logic array or PLA and its first microcontroller, while other manufactures like Zilog and Intel launched their first microprocessors.
Some of the earliest embedded systems were guidance computers which required a very low weight and extremely high reliability level that could not be otherwise attained. Early examples are the Apollo Guidance Computer used by NASA from 1966 to 1975 and the systems used on the Minuteman nuclear missiles from 1962 to 1970.
Since then we come across tons of embedded systems in our daily life, like traffic lights, television and entertainment systems, phones, cameras, home appliances, computerized industrial equipment, measurement devices, medical instruments and hundreds of small systems in our cars.
The key advantages of an embedded system are that it can reduce the size, weight and cost of an electronic system while improving its performance and reducing the probability of failure. A well designed embedded system will be perfectly optimized and debugged to fail as little as allowed by the hardware and software it comprised of, and often will require no human intervention to resume normal operation if an error occurs. This is why careful planning, wide knowledge and extensive testing are critical, more so in devices where human lives are at stake.