All computer memory, whether 'ROM' or 'RAM', is addressed. This means that every location in the memory has a label, usually a number but this is an arbitrary convention. It is important to understand the distinction between the address and the contents of a memory location. Each location is known by its address. For instance the first two letters of this chapter, 'It', are at this moment sitting in RAM locations 6446 and 6447 of my computer, which has 65,536 RAM locations altogether. At another time, the contents of those two locations will be different. The contents of a location is whatever was most recently written in that location. Each ROM location also has an address and a contents. The difference is that each location is stuck with its contents, once and for all.
