On 02/01/2011 03:03, William "Chops" Westfield wrote:
> Whatever happened to P-code (for pascal), anyway?  It seems (?) that
> interpreters in general have advanced in the relatively recent past;
> were there enough advantages in the p-code runtime environment to
> think about doing that again, or have the (older) advances made in
> compiler technology made it uninteresting anyway?  (I never noticed
> whether P-code added run-time capabilities to a typical CPU, or was
> just a crutch so people wouldn't have to write code generators.)
>
> BillW
Doesn't Java, VB6 and  .Net all use a type of "p-code" on a virtual=20
machine.  I believe true ".net code" is not x86 but portable to .net=20
implemented on any architecture being derived from MS Java machine, the=20
J++ project?

So I go and have a look ...

MS P-Code as produced by VB6, may or may not be related=20
http://en.wikipedia.org/wiki/Microsoft_P-Code
<< Microsoft's P-Code, short for packed code, is an intermediate=20
language that provides an alternate binary format to native code for any=20
compiled binary (eg: DLLs, ActiveX controls, or Applications). >>

<< Programs written for the .NET Framework execute in a software (as=20
contrasted to hardware) environment, known as the Common Language=20
Runtime (CLR). The CLR is an application virtual machine so that=20
programmers need not consider the capabilities of the specific CPU that=20
will execute the program. >>
http://en.wikipedia.org/wiki/.NET_Framework

<< James Gosling cites UCSD Pascal as a key influence (along with the=20
Smalltalk virtual machine) on the design of the Java virtual machine.>>
http://en.wikipedia.org/wiki/UCSD_p-System

ARM has Jazelle which is added Java byte code support. That's a bit like=20
P-Code support. There was Western Digital chip set that ran UCSD p-code =20
as its instruction set in 1980s.
http://en.wikipedia.org/wiki/Jazelle

Also intermediate stage of many languages prior to final pass to native=20
code uses *a* "p-code" language to make porting the language (new back=20
end p-code to assembler) and split optimisation between source=20
optimisation and target cpu optimisations. JALV2 is one.

On 02/01/2011 03:03, William "Chops" Westfield wrote:
<<  Whatever happened to P-code (for pascal), anyway? >>

Seems the concept is alive and well  ^_^
--=20
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