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From: hwe@beta.UUCP (Skip Egdorf)
Newsgroups: comp.os.vms
Subject: Re: bsd unix vs. dec's vms
Message-ID: <5548@beta.UUCP>
Date: Sun, 24-May-87 10:25:52 EDT
Article-I.D.: beta.5548
Posted: Sun May 24 10:25:52 1987
Date-Received: Sun, 24-May-87 19:43:54 EDT
References: <5828@shemp.UCLA.EDU> <34ab0e42.8be4@apollo.uucp> <19385@sun.uucp>
Organization: Los Alamos Natl Lab, Los Alamos, N.M.
Lines: 42
Summary: more "Why DCL only?"

>In article <19385@sun.uucp>, landauer@sun.uucp (Doug Landauer) writes:
>> Look at it from DEC's point of view at the time that DCL was designed:
>> the PDP-11 was the single most successful computer (in terms of units
>> shipped) in the history of computing.  [ or damn close -- anyone know
>> for sure? ]   DEC *had* to continue to support it.
>> 
>> They had gone through an awful fiasco on the PDP-11 where DEC
>> themselves sold *five* different operating systems for that machine
>> (maybe more -- let's see, DOS, RT-11, RTOS, RSX-11M, and RSX-11D which
>> became IAS).  And to the great chagrin of their in-house OS
>> programmers, there were as many PDP-11s running Unix as were running
>> some of their own operating systems.  DEC needed some consistency at
>> that point.  The motivation for designing DCL was to prevent something
>> like that from happening on the VAX, without abandoning their enormous
>> installed base of PDP-11 users.  They wanted a single OS to be dominant
>> on the VAX line, and at that they've been almost totally successful.

I think that a more important historical perspective involves the
DecSystem-10 and DecSystem-20 series.
In the late '60s and early '70s, TOPS-10 on the DEC-10 was the sort
of "in" operating system that Unix is today. Everyone who was a true
computer guru had to use one (the AI labs, etc.).
(as a former TOPS-10 user, this reputation was solidly based...).
One of the real marketing strengths was the single operating system
used by the whole line of machines, TOPS-10.

The ARPANET community had been playing with some upstart called TENEX.
(Golly, does this story sound familier to VAX folks?)
It became clear that DEC would have to support TENEX in some form
as well as TOPS-10, and there were internal wars over this drastic
step. The multi-OS group won, and DEC introduced the DecSystem-20
with a new operating system called TOPS-20 (TENEX).

The single-OS group in DEC saw the 10/20 start to fade, and fought
even harder to have only one OS on the new VAX.


Would someone with more first-hand knowledge of the internal battles
over this within DEC care to comment?

				Skip Egdorf
				hwe@lanl.gov