Re: Interpreter for old basic programs from the line number era

On Mar 19, 9:32=A0am, Charmed Snark <sn...@[EMAIL PROTECTED]
> wrote:
> winston19842...@[EMAIL PROTECTED]
 expounded
innews:79cbe0c2-b809-43b4-9b75-62f966b=
e745f@[EMAIL PROTECTED]
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> > On Mar 18, 11:41 pm, Eric <englere_...@[EMAIL PROTECTED]
> wrote:
> >> On Mar 18, 6:18 pm, winston19842005 <bjjlya...@[EMAIL PROTECTED]
> wrote:
> >> > On 3/18/08 3:52 PM, in article
> >> > Xns9A65A9BDEA2B5SnarkCharmedImS...@[EMAIL PROTECTED]
 "Charmed Snark"
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> >> > <sn...@[EMAIL PROTECTED]
> wrote:
> >> > > Eric expounded in news:f1e8dd88-0800-4725-98ee-8ad4fa188ee5
> >> > > @[EMAIL PROTECTED]
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> >> > >> On Mar 6, 5:26 pm, Guy Macon <http://www.guymacon.com/>
wrote:
> >> > >>>> There's Cheesecake BASIC V 3 that does.
> >> > >>>>http://noktosoft.megafolio.com/
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> >> > >>> Now that is cool! "Cheesecake BASIC is written in BASIC, and
> >> > >>> can be compiled with the PowerBasic Console Compiler (2.0 or
> >> > >>> above), with QuickBASIC 4.5, or with Cheesecake BASIC V3"
> >> > > ..
>
> >> > >> Remember that the term Virtual Machine is just a fancy term that
> >> > >> means the runtime interpreter that executes the p-code
> >> > >> instructions. "cvm" is the Cheesecake virtual machine. Once this
> >> > >> is compiled it is called the "RTL".
> >> > > ..
> ..
> >> > > Wikipedia states (http://en.wikipedia.org/wiki/Virtual_machine)
> >> > > that the term was "originally defined by Popek and Goldberg as an
> >> > > efficient, isolated duplicate of a real machine. Current use
> >> > > includes virtual machines which have no direct correspondence to
> >> > > any real hardware."
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> >> > > I can't recall if JVM was based on any real hardware. I seem to
> >> > > recall Sun was making some noise about JVM hardware at one time.
> >> > > But I suspect that in Java's case, Java byte code came long
> >> > > before any real hardware ever existed.
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> >> > Google UCSD Pascal. It was byte-code, for a virtual machine. UCSD
> >> > Pascal involved porting an interpreter written to each processor.
> >> > The environment (OS) was written in itself. It compiled to p-code
> >> > (one of the first uses of this terminology).
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> I remember well p-code and UCSD Pascal, although I never used it much
> myself (at the time I was more of a C biggot). You couldn't really live
> through those years without being aware of them.
>
> But the question that I raised wrt to Java, was whether or not a real
> machine existed when its byte code was "created". The same could be
asked
> about p-code - agreed that hardware did subsequently exist for it.
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> >> Yes, although UCSD wasn't the first Pascal compiler to use p-code it
> >> was the most popular by far. It used an especially compact variation
> >> that was well suited for 8-bit CPUS.
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> Yep yep.
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> >> > If you Google Java, you will often find references to UCSD Pascal.
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> I know. It would be difficult not to find those comparisons.
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> >> The JVM is cool. The earlier versions were even hobbiest friendly.
> >> But it has gotten way too complicated now. I looked at the source Sun
> >> released, and it's a monster!
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> Somehow, I _don't_ doubt that. =A0;-)
>
> Warren.
>
> --
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The original bytecode was O-code which the original BCPL compiler used
as its target back in 1967. This made BCPL very portable of course,
and indeed it was widely ported at the time. One slight difference
between O-code and later bytecodes was that it was intended to be
compiled to native code, rather than interpreted. So although O-code
could have been interpreted by an O-code Virtual Machine, it generally
wasn't. Sadly this combined portability/native code advantage was lost
when C was developed, so it's good to know that both Java and C# have
brought it back more recently.

Cheers

Derek