Re: A83: Re: ROM calls

To: assembly-83@lists.ticalc.org
Subject: Re: A83: Re: ROM calls
From: "Revenant" <revenant_1@hotmail.com>
Date: Wed, 29 Jul 1998 12:22:28 PDT
Delivered-To: assembly-83-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: assembly-83@lists.ticalc.org



>> How does the 83 know whether a call you make should call to the ROM 
or
>> call something from the RAM, as in a library routine or a subroutine 
in a
>> program?
>
>Rom calls are merely memory equates to places in the ROM...for labels 
I'm
>not too sure, but I know that the JR command tells the processor how 
many
>bytes to move to.  JP specifies an address in the program to jump
>to...about the call command...I'm not too sure, but its probably 
similar to
>JP...not sure though. :)
>
>James.
>
>PS:  Thanks for the highscore thing!

The call command moves the stack pointer (SP) and the program counter 
(PC). Like this: -SP=PC,PC=nn where nn is the location being called.

Revenant

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com

Follow-Ups:

Re: A83: Re: ROM calls

From: Olle Hedman <oh@hem.passagen.se>