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From: cs4e3bb@maccs.UUCP (Ray Wong)
Newsgroups: comp.sys.atari.st
Subject: Code launching on the ST
Message-ID: <134@maccs.UUCP>
Date: Sun, 23-Nov-86 12:21:09 EST
Article-I.D.: maccs.134
Posted: Sun Nov 23 12:21:09 1986
Date-Received: Thu, 27-Nov-86 17:50:11 EST
Reply-To: cs4e3bb@maccs.UUCP (Ray Wong)
Distribution: na
Organization: DCSS, McMaster University
Lines: 26

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I have a question that may be considered trivial by most
however this information does not appear in any tech info I 
have read.

When you are writing an assembler program on the ST, as I understand
it, you do not know where the actual run-time address of the program
will be.  Therefore much of the techinical literature recommends that
you write relocatable code.  However, how do you deal with instructions
such as "jsr $XXXX" ???  Now, I know the 68000 has many PC based
addressing modes, however it seems that you have to go to a lot of
trouble just to calculate the jump address at runtime just for a
subroutine call.
My question is this, does the ST support some sort of runtime loader
that works with your assembler, i.e. does GEMDOS support loader tables
which translate ABSOLUTE locations into their appropriate run-time 
addresses??
Also, what EXACTLY is the mechanism used by TOS for launching 
 a xxx.prg ( xxx-don't care  ) from the Desk Top????
(i.e.  Where does it load the program, What location of the program
       does it begin executing at?? )

                    .... Thanks in advance for any help

                              Ray Wong