[Info-vax] OS Ancestry

[Bill Gunshannon]

On 5/13/21 8:52 AM, Arne Vajhøj wrote:
> On 5/13/2021 8:21 AM, Bill Gunshannon wrote:
>> I have become very curious about the ancestry of VMS.  (I am
>> going to look into some others, but for VMS I do have this
>> outlet for information!)
>>
>> Both Primos and Unix came from people recently working on
>> Multics.  Primos went in the same direction as Multics while
>> Unix appeared to go in a very different direction.
>>
>> VMS is more similar to Primos than Unix.  I have seen it said
>> that RSX-11 was the immediate parent of VMS.  Was that true?
>> Given that, what is the ancestry going back even further?
>> Where did VMS actually get its start paradigm-wise?
>>
>> Anybody here have any of this information?
> 
> The story in Wikipedia is:
> 
> https://en.wikipedia.org/wiki/OpenVMS
> 
> <quote>
> In April 1975, Digital Equipment Corporation embarked on a hardware 
> project, code named Star, to design a 32-bit virtual address extension 
> to its PDP-11 computer line. A companion software project, code named 
> Starlet, was started in June 1975 to develop a totally new operating 
> system, based on RSX-11M, for the Star family of processors. These two 
> projects were tightly integrated from the beginning. Gordon Bell was the 
> VP lead on the VAX hardware and its architecture. Roger Gourd was the 
> project lead for the Starlet program, with software engineers Dave 
> Cutler (who would later lead development of Microsoft's Windows NT), 
> Dick Hustvedt, and Peter Lipman acting as the technical project leaders, 
> each having responsibility for a different area of the operating system. 
> The Star and Starlet projects culminated in the VAX-11/780 computer and 
> the VAX/VMS operating system. The Starlet name survived in VMS as a name 
> of several of the main system libraries, including STARLET.OLB and 
> STARLET.MLB.
> </quote>
> 
> https://en.wikipedia.org/wiki/RSX-11
> 
> <quote>
> RSX-11 is a discontinued family of multi-user real-time operating 
> systems for PDP-11 computers created by Digital Equipment Corporation. 
> In widespread use through the late 1970s and early 1980s, RSX-11 was 
> influential in the development of later operating systems such as VMS 
> and Windows NT.
> ...
> RSX-11 began as a port to the PDP-11 architecture of the earlier RSX-15 
> operating system for the PDP-15 minicomputer, first released in 1971. 
> The main architect for RSX-15 (later renamed XVM/RSX) was Dennis “Dan” 
> Brevik.
> ...
> The porting effort first produced small paper tape based real-time 
> executives (RSX-11A, RSX-11C) which later gained limited support for 
> disks (RSX-11B). RSX-11B then evolved into the fully fledged RSX-11D 
> disk-based operating system, which first appeared on the PDP-11/40 and 
> PDP-11/45 in early 1973. The project leader for RSX-11D up to version 4 
> was Henry Krejci. While RSX-11D was being completed, Digital set out to 
> adapt it for a small memory footprint giving birth to RSX-11M, first 
> released in 1973. From 1971 to 1976 the RSX-11M project was spearheaded 
> by noted operating system designer Dave Cutler, then at his first 
> project. Principles first tried in RSX-11M appear also in later designs 
> led by Cutler, DEC's VMS and Microsoft's Windows NT.
> </quote>
> 
> https://en.wikipedia.org/wiki/PDP-15#RSX-15
> 
> <quote>
> RSX-15 was released by DEC in 1971. The main architect for RSX-15 (later 
> renamed XVM/RSX) was Dennis "Dan" Brevik.
> 
> Once XVM/RSX was released, DEC facilitated that "a PDP-15 can be 
> field-upgraded to XVM" but it required "the addition of the XM15 memory 
> processor."
> 
> The RSX-11 operating system began as a port of RSX-15 to the PDP-11, 
> although it later diverged significantly in terms of design and 
> functionality.
> </quote>
> 
> All before my time.
> 
> But I do remember that VAX and VMS VAX had some PDP-11 and RSX-11
> compatibility mode features.
> 
> Arne


Thank you.  That takes me back a little bit further.  But I fear the
very origins, the driving model, may be long lost by this time.  I
have a number of very early textbooks on Operating Systems and none
of them describe features common in VMS or RSX.  It's really just
curiosity, but I wondered where some of the concepts originated.

bill