原创 What exactly is an embedded system?

Originally, I was invited to present a paper introducing FPGA technologies (devices, tools, and design flows). As I always say, the real trick is to get me to stop talking -- now I'm going to give an additional presentation that I've tentatively titled: "Robot Apocalypse: Trends in Embedded Systems."

Of course, this leads us to the perennial question: "Just what is an embedded system?" Actually, I would like to take this a little further. When did the term "embedded system" come into being and to what did it apply at that time? It would also be interesting to know how what has been understood to be an embedded system has evolved over the years.

I posed the "What is an embedded system?" question to embedded guru Jack Ganssle, who replied:

The usual definition of embedded system (ES) is along the lines of a device with a single bit of functionality. But, that means a cell phone is not one, and one could certainly argue the opposite. Also, this definition would mean a blade sever, which is really just a PC, is an ES.

My definition is one no one likes: An ES is a computer-based system with an extremely high quality bar. PCs can crash, ESs can't.

 

I've also heard definitions along the lines of an embedded system being one without a screen or keyboard, but that was when people were trying to come up with a definition that excluded things like laptop computers.

Personally, my favorite definition is as follows: "An embedded system is one you don't even know is there... until it stops working." Although this sounds good, however, it really doesn't cover all of the bases.

How about you? What's your definition of what an embedded system is (or isn't)? Also, do you know when people first started using this term, and can you recall how the definitions of things that have been considered to be (or not to be) embedded systems have evolved over the years?