One of the annoyances that I run into due to my job as a software engineer is that when I tell most people that I’m a software engineer is that most people get that I work with computers. Unfortunately, they assume that this means I work with personal computers, which usually leads to them uttering the phrase, “You know, I’m having problem with Windows, and…” That’s usually when I have to stop to them and explain to them that when it comes to the PC world, I’m only slightly more knowledgeable than the average user. Most of my professional expertise is in the world of embedded systems.
Of course, part of the problem is that the average person doesn’t really understand what an embedded system is. They’re naturally inclined to think “computer” and picture that machine with a monitor, keyboard, and mouse they have sitting on their desk. So that usually leaves me racking my brain figuring out the best way to explain what an embedded system is.
Today, while talking to Tracie, I realized that I’ve been overlooking a perfect example of an embedded system (though the more geekish might argue how accurately said example can really be called an embedded system) that everyone is familiar with. In fact, three different flavors of this example are quite popular now, the Xbox360, the Nintendo Wii, and the Playstation 3. In the loosest sense, gaming consoles are embedded computer systems.
For those who may not know what an embedded system is, it is a “computer” system that is designed and programmed to perform a dedicated task, as opposed to a general purpose computer — most notably a PC — which is designed to be highly configurable and usable for just about any task. A game console fits this definition quite well in that it is a computer system designed to do exactly one thing: Allow a user to play games.
Most importantly, as an example of an embedded system, the gaming console excels in that it shows the advantage of embedded systems over general purpose computers. After all, a user can play games on his PC as well. However, because the PC is designed for multiple purposes, playing a game on a PC incurs a great deal of overhead. The game software has to interface with a rather complex operating system that has been highly abstracted and work with (or bypass, which is just as problematic) the operating system’s device drivers in order to access resources like the keyboard, mouse, game controller, and graphics controller. If there are other applications running in the background, the game has to be able to play nice with them as well. The net result is that games can run slow on a PC. Anyone who has played many graphics intensive games on a PC will notice that there are just times when the image or sound lags while the computer tries to catch up. This is usually because the operating system or some other application has been doing things to steal resources from the game.
Like any embedded system, a gaming console doesn’t have this problem. The core operating system on the console is bare bones, and designed to support the current game being played. Because of this, the game has access to all of the system’s resources and doesn’t have to worry about another application jumping in and slowing it down. More importantly, the interface to devices like the graphics controller, game controller, and audio controller are much simpler and less abstracted. In fact, while I cannot say so for certain, it would not surprise me if most console games access these devices at the hardware level directly rather than going through any device driver at all. Again, with an embedded system serving a single dedicated purpose, this is not only possible, but perfectly acceptable.
Of course, as I said, a game console is not a perfect example. After all, they are still far more configurable and less dedicated than more traditional embedded systems, such as the electronic computer module that controls the fuel injection process in your car. The game console can accept different games, which will provide different software and a different gaming experience for the user, which makes it slightly more “general purpose” than some purists might consider worthy of being declared an embedded system. However, as a coworker pointed out a few months ago, this is a problem in the world of embedded systems in general. With the increasing features being added to cell phones and PDA’s (two other devices that have tradtionally been considered embedded systems), the line between general purpose computers and embedded computers is becoming increasingly blurred every day.