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From: munck@chance.uucp (Robert Munck)
Newsgroups: comp.os.misc
Subject: Re: Operating systems
Message-ID: <72766@linus.UUCP>
Date: 5 Oct 89 11:58:34 GMT
References: <6649@hubcap.clemson.edu> <15064@netnews.upenn.edu>
Sender: news@linus.UUCP
Reply-To: munck@chance.UUCP (Robert Munck)
Organization: MITRE-McLean Software Engineering Laboratory
Lines: 44

In article <15064@netnews.upenn.edu> ferris@eniac.seas.upenn.edu.UUCP (Richard Ferris) writes:
>I have used two IBM mainframe operating systems: TSO and CMS.
>... MVS as the new operating system....
>what is ... that OS and whether it ... replaces CMS or runs under it ...
>
>ferris@eniac.seas.upenn.edu

Eniac is a node on the Internet?  Jeez, I thought the thing wouldn't even
run anymore because they couldn't get the right vacuum tubes.

Anyway, your terminology is a bit confused.  TSO and CMS are not really OSs
in their own right, but subsystems that run under other OSs.  CMS was at one
time capable of running as an OS on a bare /360, but I believe that ability
is long lost.  It ran originally as an OS on a virtual machine under CP-40,
a virtual machine Control Program running on a /360 mod 40 with a special
DAT (Dynamic Address Translation) box that gave the 40 virtual memory.

When the /360 mod 67 came along and TSS wasn't quite as wonderful as Big
Blue said it would be, CP and CMS were naturals to move to that machine,
becoming CP-67/CMS.  With their next generation, IBM declared that they
had invented virtual memory (surprising the people at Burroughs and various
other places) and put CP/CMS on the new machines, eventually renaming
it VM/370.  The combination of VM and CMS has been greatly loved by IBM
customers for nearly a quarter century and hated by large parts of the
IBM organization.  CMS (originally Cambridge Monitor System, for the
IBM Cambridge Scientific Center where it was developed) is as good a
program development environment as IBM has, though that's not saying
much.

TSO (The Slow One) came along a bit later, say late 1960's, as an interactive
subsystem under the "main" OS for the /360, MVT.  It is fairly universally
hated by users and loved by IBM and user management.  MVT has become MVS and
various other acronyms on the /370 and later generations.  TSO is essentially
a special user program running on the OS and in tentative communication with
interactive terminals.  It is rumored that the last attempt to compile a
program over 10K lines interactively has been executing on a 6-CPU mainframe
in Maryland since late 1987.  (TSO is not an especially usable programmer
environment).

These are, of course, my personal opinions.
                              -- Bob Munck
                 -- Bob <Munck@MITRE.ORG>, linus!munck.UUCP
                 -- MS Z676, MITRE Corporation, McLean, VA 22120
                 -- 703/883-6688