Basicly I think its about integrations and transistor equivalents, but this is just linear to the size of memorys. In fact, to come back to the original question, Arfon just took doubling of address space and doubbling of data bus width for the same thing, but in fact they are two different functions - widening data bus is linear, while widening address bus is to the square (sorry, my mathematical english just stops here). This means doubble the data bus just doubbles the date transfer rate (the only thing the data bus is needed for) or w'=w+w. But doubbling the address bus is putting the address range (and thats what the address bus is for) to the square or r'=r*r. So, while a 256 or 512 bit data bus is usefull (and already in use in main frames - only called data path), even a 128 Bit address bus is just nonsense. Gruss H. -- Ich denke, also bin ich, also gut HRK