Which Dec Emulation is the MOST useful and Versatile?

[Dave Wade]

Folks,
 Well I have now found one of Crispin Rope and Mark Priestly's papers on
ENIAC

http://eniacinaction.com/docs/AddressableAccumulators.pdf

It says

"ENIAC's original control method was modified in 1948, after which point its
wires and switches were left mostly untouched while it ran only a single
(but slowly evolving) program: a microcoded interpreter for a virtual von
Neumann architecture machine."

And 

"ENIAC's application programs were written as a series of two digit
instruction codes for this virtual machine and loaded into its read-only
function table memory by turning knobs to set digits."

I would therefore argue that "emulation" is as old as computing itself...

Dave Wade
G4UGM


> -----Original Message-----
> From: Dave Wade [mailto:dave.g4ugm at gmail.com]
> Sent: 29 October 2017 15:54
> To: 'Paul Koning' <paulkoning at comcast.net>; 'General Discussion: On-Topic
> and Off-Topic Posts' <cctalk at classiccmp.org>
> Subject: RE: Which Dec Emulation is the MOST useful and Versatile?
> 
> > -----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...
> 
> https://en.wikipedia.org/wiki/Universal_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
> 
> https://en.wikipedia.org/wiki/ENIAC#Improvements
> 
> 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
> emulation,
> > done using a particular implementation approach.  At least for some of
> > the emulator features -- I believe you're talking about the 1401
emulator.
> IBM
> > 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
> seems
> > 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
> limit
> > 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
> one
> > in IT (consider "data set").  And in particular, as was pointed out
> before,
> > "emulator" has a quite specific (and different) meaning in the 1980s
> through
> > 2000 or so in microprocessor development hardware.
> >
> > 	paul
> Dave