Where should the type information be: in tags and descriptors 449

In this case, the TOPS-20 system was brought in because they were already familiar with DEC from the 11-70, rather than the other way around, but that doesn't change the basic argument, I mention it simply for geeky completeness.

There certainly was considerable benefit for interoperability and personnel cross-training to having the computers come from the same manufacturer, generally and in that period.

Certainly the -20 didn't deliver as much usable user-computing as the -10 in most environments. In fact, it's an example of the users wanting to spend more cycles on user interface, though a less extreme example than GUIs. Pure compute performance wasn't the only important thing; using the time of the *people* more effectively was also important, and becoming more so (as the compute cycles got cheaper over time). (And then we get people who *would* benefit from learning to use a better interface, but don't wish to do so.)

My experience with DEC computers went from PDP-8 (-I running TSS-8 and -L running COLPAC, no real OS) to PDP-11 RSTS to TOPS-20 to VMS. I have a hard time seeing the kind of difference in kind you seem to be describing between RSTS and TOPS-20 and VMS.

Certainly all the non-VMS people were being stomped out; corporate had adopted the "one company, one egg, one basket" policy, with VMS as the egg, so everything else was being de-emphasized. But what end DEC was missing the PC revolution, not the loss of timesharing. The results would have been the same if they'd aggressively continued all the existing product-lines, I think, so long as they hadn't found a way to push into the desktop market.

(Several of my statements above are fairly speculative, despite being phrased as simple buttertions. I don't *actually* know what would have happened if things had been done differently, of course!)

I didn't know any -10 sites in the field, so I can't comment on whether that worked differently. *Most* of the sites I knew, though, didn't have *any* of the 36-bit line in them. And often the -11s were living in niches in between other manufacturers -- like First National Bank St. Paul which (in 1975) had Burroughs mainframes, but had brought in an 11 to do some *more interactive* systems for derivative security pricing and then for fed funds wire-transfer. I saw DEC building up from the bottom mostly, rather than down from the top. --