Except for the fact that much of the work done at Xerox PARC during the 70s was an attempt to produce the software that such a device would run, in anticipation

Except for the fact that much of the work done at Xerox PARC during the 70s was an attempt to produce the software that such a device would run, in anticipation of the day, decades hence, when it would be practical (given Moore's law, etc).