Digital Standard Mumps

Paul Koning paulkoning at
Thu Apr 18 18:11:35 CDT 2019

> On Apr 18, 2019, at 3:06 PM, Warner Losh <imp at> wrote:
> On Thu, Apr 18, 2019 at 12:41 PM Dan Veeneman via cctalk <cctalk at> wrote:
> On 4/18/2019 2:27 PM, Paul Koning via cctalk wrote:
> > my memory is that DSM-11 is an operating system all its own, not just a language processor running on top of a standard OS like RSTS.
> In the late 1980s and early 1990s, we used DSM running on VMS 4.7 for a
> nationwide (United States) mortgage credit reporting system.
> The big claim to fame for RSTS/e  was I thought that it let you load 'foreign' executives so you could run RT-11 or RSX-11 or whatever binaries all on one system. I'd imagine DSM-11 images would be easy if it were a real OS. I'd always thought of RSTS/e as a poor-man's hypervisor. But maybe I'm misremembering how much it could do...

Poor man's hypervisor, I like that.

That's reasonably accurate.  RSTS/E had "run-time systems", originally the interpreter, support library, and user interface of the BASIC-PLUS language machinery.  Starting in, I think, RSTS/E V5B, it was generalized step by step to become a collection of such things: a user interface, execution environment, and other stuff.  It might be very narrowly tailored, like the TECO run-time system, it might be the interpreter library for a language, like the FORTH and ALGOL run-time systems, or it might be a fairly complete emulation of a different OS, like the RT11 and RSX run-time systems.

I first used a very primitive version of this feature in V5B around 1975, to run an assembly language program before there was any general RSTS support for doing that.  


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