Stored program architecture

The defining feature of latest computers which distinguishes them from all other machines is that they can be programmed. That is to say that a set of instructions (the program) can be given to the computer and it will store them and carry them out at some time in the future.

In most cases, computer instructions are simple: add one number to another, move some data from one place to another, send a message to some external device, etc. These instructions are read from the computer's memory and are useually carried out (executed) in the order they were given. However, there are geneally specialized instructions to tell the computer to jump ahead or backwards to some other place in the program and to carry on executing from there. These are called as "jump" instructions (or branches).