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From: matt@physics16.berkeley.edu (Matt Austern)
Newsgroups: comp.sys.handhelds
Subject: Questions about internal RPL programming on the hp48
Message-ID: <MATT.91Mar6104540@physics16.berkeley.edu>
Date: 6 Mar 91 18:45:40 GMT
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Reply-To: matt@physics.berkeley.edu
Organization: Lawrence Berkeley Laboratory (Theoretical Physics Group)
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I've just started trying to write programs in machine language and
internal RPL, and there are a few (probably very basic) points that I
have questions on.  Would someone out there like to enlighten me?

First, I don't understand what is meant by calling internal RPL code
"threaded."  (Perhaps this just means I've never used forth.)

Second, I don't understand the difference between, for example, #1592D
and #18AA5.  These are documented in Derek Nickel's internals list as,
respectively, "Set last RPL token to <0h> and verify DEPTH >= 1" and
"Save last RPL token and verify DEPTH >= 1".  I suppose my problem is
that I don't understand what is meant here by "last RPL token".

Finally (and this is perhaps the only nontrivial question), does
anybody know if there is a good way to use local non-stack storage in
an internal RPL program?  That is, is there a way to use local
variables or the equivalent?

Thanks to everyone who has posted their findings about hp48 internals;
this information has been extremely useful.
--
Matthew Austern                   Just keep yelling until you attract a
(415) 644-2618                    crowd, then a constituency, a movement, a
austern@lbl.bitnet                faction, an army!  If you don't have any
austern@physics.berkeley.edu      solutions, become a part of the problem!