many years ago, computers were not "personal"in any way. They were enormous and hugely expensive, and they required a team of engineers and other specialists to keep them running. these early PCs could not perform many of the useful tasks that today's computers can. later , in the 1970s, a new type of computer , pc or personal computer, started to gain in popularity. to day, pcs are everywhere you look. you probably already own at least one of these types of PCs. laptop,desktop computer. PDA or personal digifat PCs, etc. But not all types of computers are obvious as the ones above. there are still other kinds of computers that fit inside of other devices and control them these computers are known as embedded systems which can be tound in traffic lights, TV sets, refrigerators and many more devices.