[Simh] Regarding "Cutler THE father of VMS" myth

Sergey Oboguev oboguev at yahoo.com
Tue Mar 3 20:28:25 EST 2015

> ----- Original Message -----
> From: Christian Gauger-Cosgrove <captainkirk359 at gmail.com>
> To: Bill Cunningham <billcun at suddenlink.net>
> Cc: SIMH <Simh at trailing-edge.com>
> Sent: Tuesday, March 3, 2015 12:12 PM
> Subject: Re: [Simh] Getting rsxs to run on the pdp11 emulator

> Dave Cutler is the "father" of RSX-11/M+, VMS, and Windows NT.

Since the topic of "Cutler the Demiurg of VMS" comes up once in a while here
and there...

In the interests of some historical justice and accuracy, Cutler is "a" father
of VMS, not "the" father.

The myth that Cutler was "the" father of VMS originated in its public
circulations probably from the authors of the "Showstopper" book, who did not
have much interest in the subject of VMS, did not have access to the members of
early VMS design team and could not know what had been happening there, and
also probably (as many if not most book authors) were not against dramatizing
and embellishing their story a little.

I have not read or heard anywhere that Cutler himself was ever claiming the
role in VMS development ascribed to him by this myth.

In reality, from the very start there were three key people on the software
side in development of VAX and subsequently VMS, and if any "the" father of VMS
were to be named at all, it would hands down be Dick Hustvedt.


Cutler was a technical team manager during the development of initial versions
of VMS, however he was not the top #1 architect and technical contributor.

"VAX Team A" designing VAX architecture included 3 people from the hardware
side and 3 people from the software side. On the software side these were
Dick Hustvedt, Peter Lipman and David Cutler. These three also became later
the principal authors of VMS kernel.

In terms of the magnitude of contribution to VMS among these three
a distinct #1 was certainly Hustvedt.

A look into VMS source code (authorship and change history in source files
headers) in source kits at around VMS late 3.x-4.0 versions timeframe -- about
the time when all three departed VMS development -- makes the picture
exceedingly clear.

Direct code contributions of Cutler to VMS were parts of the kernel, DCL, MCR,
autoconfig, 5 drivers and C run-time library.

As to the specific parts of VMS kernel, the breakdown of its primary authors
is as follows:

Cutler was responsible for IO subsystem (except page locking), forking (like in
fork processes/fork blocks), exception handling, system timer and timer
services, executive pool allocation, bugcheck code, logical names and several
miscellaneous facilities (including mailboxes, console IO routines, CHMx
dispatcher, adjust stack and error logging interface routines in the kernel).
There are no visible Cutler "fingerprints" (change/authorship comments) in any
other kernel modules.

Hustvedt was the primary author responsible for the scheduler, swapper,
synchronization primitives (including event flags and kernel mutexes) and RSE
code (that changes process scheduling state in response to system events), AST
handling (for all CPU modes), process creation/deletion/starting, process
control (suspend/resume/hibernate/wakeup/handling process priorities and
names), process shell and null process, system init, SYSGEN parameters,
image exit and rundown, power failure handling and recovery, VMB, SYSBOOT,
XDELTA and MSCP port driver.

In addition, as a secondary author Hustvedt was responsible for 55 other source
files in the kernel.

Later Hustvedt was also responsible for ASMP (asymmetric multi-processing) and
was the driving force behind the advent of VAXcluster.

Peter Lipman was the primary author responsible for all virtual and physical
memory handling (except swapper). This may sound brief, but these are the most
complex and sophisticated modules in the system with extreme importance.
One should remember that the ability of VMS to run scores of user sessions
in a few megabytes of main memory was a sort of a technical wonder that,
one might surmise, greatly contributed to VMS success. In the course of
VAX MP project, I had a reason to look through some pieces of these algorithms
and implementation code behind them and might say they stay a technical miracle
even today, with hardly any modern operating system replicating their
complexity and sophistication (of course, in days of RAM plenty this is not
much of a pressing issue). In addition, Lipman was responsible as the primary
author for image activator, kernel file IO routines and GETDVI. As a secondary
contributor he was also responsible for 63 other source files in the kernel.

There were also other major VMS components, such as file system, various system
processes, later SCA/SCS etc., developed by other people.

Thus, though contributions of Cutler to VMS were significant, he by no means
was "the demiurge" of VMS as the myth would have it, nor even the architect #1.

One may surmise that dedication of I&DS to Hustvedt (rather than Cutler, who by
the time the book was published also departed VMS development) was not only a
"thank you" by grateful colleagues after the tragedy that happened to Hustvedt
and also owing to the "social" role Hustvedt played inside the team (in his
social skills Hustvedt is generally remembered to be the opposite of Cutler, as
a very friendly person always willing to help, to explain and to teach), but
also a reflection of his technical and architectural contribution to VAX/VMS.

Hustvedt, who was the key focal point in the VMS team, tragically suffered car
accident in 1984 that left him brain-damaged.


Here he is pictured (on the left) next to Andy Goldstein, another key VMS


Besides Hustvedt's key contribution to the initial development of VMS, he was
also the driving force behind the development of VAXcluster, at a time when
Cutler already departed VMS engineering.

Lipman departed DEC in 1984 to become a key person in the development of
fault-tolerant systems in Tandem, Amdahl and subsequently HP.


This is not to diminish Cutler's real contribution to VMS -- it was quite
significant, significant enough not to need mythical embellishment by
positioning him as "the" father of VMS.

More information about the Simh mailing list