Which Dec Emulation is the MOST useful and Versatile?

Dave Wade dave.g4ugm at gmail.com
Sun Oct 29 10:53:53 CDT 2017

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Paul
> Koning via cctalk
> Sent: 29 October 2017 12:42
> To: Eric Smith <spacewar at gmail.com>; General Discussion: On-Topic Posts
> <cctech at classiccmp.org>
> Subject: Re: Which Dec Emulation is the MOST useful and Versatile?
> > On Oct 28, 2017, at 10:09 PM, Eric Smith via cctech
<cctech at classiccmp.org>
> wrote:
> >
> > IBM invented computer emulation and introduced it with System/360 in
> 1964.
> > They defined it as using special-purpose hardware and/or microcode on
> > a computer to simulate a different computer.

I am not sure they invented computer emulation. I think that the concept
Emulation/Simulation is as old as, or perhaps even older than computing.
Whilst it was a pure concept Alan Turing's "Universal Turing Machine" was a
Turing machine that could emulate or simulate the behaviour of any arbitrary
Turing machine...


.. and somewhat later when ENIAC was re-wired to execute programs stored in
the function switchs, this was a partial simulation/emulation of EDSAC


well that's what Crispin Rope asserts, but his book is still copyright and I
can't find any reference to this on the net,,

> That's certainly a successful early commercial implementation of
> done using a particular implementation approach.  At least for some of the
> emulator features -- I believe you're talking about the 1401 emulator.
> didn't use that all the time; the emulator feature in the 360 model 44, to
> emlulate the missing instructions, uses standard 360 code.
> It's not clear if that IBM product amounts to inventing emulation.  It
> likely there are earlier ones, possibly not with that particular choice of
> implementation techniques.
> > Anything you run on your x86 (or ARM, MIPS, SPARC, Alpha, etc) does
> > not meet that definition, and is a simulator, since those processors
> > have only general-purpose hardware and microcode.
> >
> > Lots of people have other definitions of "emulator" which they've just
> > pulled out of their a**, but since the System/360 architects invented
> > it, I see no good reason to prefer anyone else's definition.
> "emulation" is just a standard English word.  I don't see a good reason to
> its application here to a specific intepretation given to it in a
particular IBM
> product.  It's not as if IBM's terminology is necessarily the predominant
> in IT (consider "data set").  And in particular, as was pointed out
> "emulator" has a quite specific (and different) meaning in the 1980s
> 2000 or so in microprocessor development hardware.
> 	paul

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