Chris Olds got this one. Originally, it was just another PDP, albeit with an
extended virtual address space. But then the marketeers decided it should
become the VAX 11/780 (emphasize the Virtual Address Extension, and throw an
extra zero on for good measure.)
>2. There is no 11/74.
This was to be a hot four-processor 11/70 that got killed because it would
have eventually been clobbered by the 11/780... the 16 bit PDPs were an
evolutionary dead end, and DEC decided to save the resources by killing off
the heroically high end non-VAX PDPs at this point.