The U.S. Air Force is replacing the CPUs (Central Processing Units, the "brains" of a computer) in their F-15E fighter-bombers. The ones being replaced are vintage 1988. Since then, CPUs have become fifty (50) times faster. Naturally, the new CPUs make everything work faster on the F-15E, and allows the aircrafts electronics to do many things it could not do with its original equipment. It's a common problem with warplane electronics, for upgrades to come slowly. It's just not a matter of plugging in a new CPU. Many other new chips are required, and the software has to be rewritten to take advantage of the new capabilities. This takes time, and a lot of money and testing. The air force is reluctant to invest in these upgrades, because money is always tight, and buying new aircraft, or training, often are seen as better investments. The way around this is to build more recent aircraft so that they can be more easily, and cheaply, upgraded with more powerful electronic components.