Programmed code generation: Native vs. Pcode

[David Keppel]

In article <23944 at bu-cs.BU.EDU> bzs at bu-cs.BU.EDU (Barry Shein) writes:
>Did I miss something critical here? Most lisp systems generate and
>execute there own machine code.

Many Lisp (Prolog, Smalltalk, ...) systems generate a pseudocode
rather than native instructions.  The p-code is run by an an
interpreter rather than the hardware.  Thus, as far as the hardware is
concerned, it is only the interpreter and NOT the p-code that is being
executed.

A number of more sophisticated Lisp systems DO generate native code
for themselves (as opposed to Lisp systems where you compile an
program to native code and once you start it, you can't load any more
compiled code).  These systems, however, are typically targeted for
particular machines (e.g., InterLisp for Xerox Dandylions) and thus it
is "safe" to make assumptions about the target hardware.

	;-D on  ( Me and my big segment )  Pardo