In the early days of home computers, some companies sold their programs on disks designed to be uncopyable. Consumers found that inconvenient, either because they wanted to make copies for their friends or because they wanted to make backup copies for themselves. So other software companies sold programs designed to copy the copy protected disks. One company produced a program–SuperUtility Plus–designed to do a variety of useful things, including copying other companies' protected disks. It was itself copy protected. So another company produced a program–SuperDuper–whose sole function in life was to make copies of SuperUtility Plus.