There are many other issues involved in the design of virtual memory systems and a huge amount of effort has been expended to get them to work efficiently. We have only touched on the major points.

However, virtual memory has been enormously successful and today is considered as essential as the adder or the disk drive! Even personal computers use virtual memory, even when they are not truly multiprogrammed. Since personal computers seem to lag behind mainframes by about 20 years, anything that appeared in the mainframes of the past should be showing up on the shelves of your local computer store any day now.