Some small corrections:
Data General Nova machines were popular at Xerox PARC before the Alto was developed, so one of the various instruction sets that the Alto supported was that of the Nova allowing old software to be easily ported to the new machine. Other than that, there was no relation between Xerox and Data General.
While the Alto and its successors (including the Star and specially the Dorado) were very expensive, there was the Notetaker project that would have had a huge impact if it had been released. Imagine a $3000 machine in 1979 like the future Compaq portable but with a mouse and GUI. Don't pay attention to what the Wikipedia or the Computer History Museum say about the machine, by the way, but look at the original documents instead:
The original plan was to create a Xerox microprocessor compatible with the Alto and use two 8086 for I/O. Imagine how cool that would have been! But the group was forbidden to do their own chips, though there was a division of PARC for doing just that. So the design was changed to three 8086s instead. And as neat as this was, there were plans for a cost reduced Notetaker 2. An executive flew from the east coast specially to kill the project and make sure it really died because the board had decided to keep Xerox outside of the silly microcomputer business. They changed their minds a little later and gave us a Z80 CP/M machine after IBM came out with their PC.
The only good thing about this was that the Notetaker's designer, Douglas Fairbairn, was so upset over the cancellation that he left PARC and founded VLSI Technology Inc. (VTI) which made possible for small companies to design their own chips. Like Acorn and their ARM.