Computers have lots of parts inside, all put together in one fixed way by people who make computers. A computer like that can do lots of different jobs, but can not do any one job especially well.
Maybe you have a problem that is very hard for normal computers. Your problem takes too long, or takes too many computers (which takes lots of money). You can use the parts from a normal computer, put them together in a new way, and have a different computer. If you know how, you can make a computer that does your problem a hundred times better than a normal computer does. It won’t do any other problem very well, but it does your problem.
But maybe you have two hard problems. Your new computer can only do one of them. Or maybe you change your first problem so your new computer can’t do it any more. Then you need to make a new computer for the new problem.
Normal computers have all the parts put together so you can’t change them. You have to use the parts inside the way they come from the store. There are things that have all the parts of a normal computer in them, but the parts aren’t put together. You can put them together any way you want and make a computer that does one problem really well. Later you can use the same parts over again to build as many kinds of computer as you want, for all of your problems. If you have a new problem tomorrow that you didn’t think of today, you can build a new computer for that by using the same parts again. If you think of a better way to do your problem, you can make a new computer that does it the better way. This is what a “put-back-together” computer lets you do.
The fun thing is that put-back-together computers keep getting bigger and faster all the time, so you can do bigger problems or do them faster. (Normal computers get bigger and faster too, but not as much as put-back-together computers.) If you are very good at making put-back-together computers, you can make them from small pieces, then use the small piece over and over until you use up all the parts in the put-back-together computer. Then, when you get a bigger put-back-together computer with more parts inside, you can make even more of your small pieces and get a faster computer very easily.”
— Tom VanCourt, on reconfigurable computing.