The VAX is one of the most successful computer-families of Digital Equipment Corporation (and perhaps the whole industry). The name VAX, which stands for "Virtual Address eXtension" refers to the large virtual address space, which was meant to be an extension to the PDP-11 architecture. In the first months of the project, the machine was called PDP-11/780. The hardware and the main operating system for it, VMS (Virtual Memory System) were developed parallelly.
Many thanks to Steve Rothman!
Digital started to think about a possible wide-word machine in 1973, but the early decision was to build a new 36-bit machine based on the successfull PDP-10. This new machine was to superceed the high-end of the PDP-11 line, so the strongest PDP-11, the 11/70 was developed as an interim machine until the new 36-bitter would be ready. One year later however a few people (Bill Demmer was among them) questioned whether this was the right way to go. They felt that Digital needed a machine that would made migration from the PDP-11 easy. Following that, the decision was made to consider an "extended PDP-11" alternative to the 36 bit machine. The 36-bit project, led by Len Hughes (engineering and Dave Rodgers (lead architect/project engineer/engineering supervisor) got the nickname "Unicorn", while the 32-bit machine was later called "Star". The latter took off on April 1st, 1975 (this is just an anecdote, it was a few days earlier).
The "extended PDP-11" project was led by Gordon C. Bell, and one of the main goals was PDP-11 compatibilty. The team consisting of five people (Gordon Bell, Bill Demmer, Richie Lary, Steve Rothman and Bill Strecker) created a proposed architecture, which was to be reviewed in June, 1975. The team (called VAX-A team) worked through April and May on the third floor of building 12 in the Maynard mill; the result was the so-called "VAX Blue Book" - the specification of a 32-bit machine, distributed in loose blue binders. The architecture we now know as VAX is a subset of what was originally planned: many features were dropped because they weren't economically realisable. There were two other commitees too besides team A: VAX-B and VAX-C; the first consisted of technology reviewers, the second worked on business issues. The name "VAX" was coined probably by Gordon Bell.
After the meeting in June, the "Unicorn" project got cancelled
(that's one of the reasons why 36-bit fans hate VAXen; and it only got
worse later in the mid-eighties, when the whole PDP-10/DECsystem-10/DECSYSTEM-20
line was "killed" in favor of the VAX), and the "32-bit engineers" went
on implementing their architecture, with some of the engineers of "Unicorn".
When the architecture work on paper seemed to be near its end, a few members
of the team went on to build the VAXHS, the VAX Hardware Simulator: a modified
PDP-11 for developing VMS and the FORTRAN compiler (four of these machines
were made). After this was finished, the development group took off to
design the second VAX computer ("Comet").
The VAX Timeline
Disclaimer: the pages don't focus on figures, numbers, and such. This is a history page, not the summarized edition of all technical manuals ;-)
1978. VMS1.0 shipped
1981. VAX Information Architecture
Digital Equipment Corporation, DEC, VAX, VMS, OpenVMS, PDP-11 and many other names and abreviations are registered trademarks of Compaq - which is now probably a registered trademark owned by HP (Hewlett-Packard) - , Mentec, and other companies.
All comments are welcomed, but please don't ask me for part numbers, spare parts, and don't expect answers to questions like "how do I boot up a 11/725 I found in the dust bin" and "how do I format a harddisk" in e-mail! I don't have the knowledge, nor the time to answer all the questions I get every day. Please try the newsgroups comp.sys.dec and alt.sys.pdp11, chances are that the people there know much more about PDP-11 systems, than I do, and they might help you! Good luck, I hope you all get your answers, and I'm sorry I'm not the one to tell them...
These pages were made in my free time. I did it for fun, and because it's good to see that people like the result. I would probably update them more often if I had the time, but I have to earn my living, too. And it's not the easiest thing to do around here: I mean I'm okay and am even able to travel a little bit, but I always have to choose, which one is more important: to go on a holiday? to buy myself a new camera? to get a new computer? to buy my favorite music CD's or books? or going somewhere with my girlfirend? - I can't afford these things at the same time (maybe not even in the same year). So, if you liked my pages and you feel like it, I would be mostly honoured if you'd buy me something (even something tiny!*) off my amazon.com Wish List!
*If you happen to be a millionaire searching for a way to make somebody (me!) happy, or you're Santa Claus, please feel free to buy me one of the more expensive things off this list ;-)