Topic       : The ATARI Compendium
Author      : Scott Sanders / JAY Software
Version     : 1.25 (20/6/2003)
Subject     : Documentation
Nodes       : 1117
Index Size  : 32614
HCP-Version : 6
Compiled on : Atari
@charset    : UTF-8
@lang       : en
@default    : 
@help       : %About
@options    : +g -i -t4 +y +z
@width      : 100
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                            Device Independence


Programming for compatibility on the Atari is a simple task. Here are
some basic tips:

   ∙ A GEM program should use the VDI for all graphical/screen output.
     Never use GEMDOS, BIOS, or XBIOS functions to output to the screen
     or manipulate the palette.

   ∙ Don't make assumptions about the type of display based on any call
     such as Getrez(), EsetShift(), or Vsetmode(). Only look at the
     values returned by the VDI v_opnvwk() call.

   ∙ For printing, always support GDOS. It is the only way to ensure
     that a user has a printer driver and fonts for the attached printer
     and that output is consistent among different printers. As with the
     screen, never make assumptions about the printer based on criteria
     like driver name, etc.

   ∙ Never write directly to hardware unless it's the documented way to
     accomplish a task. This is an almost sure sign that your program
     will break in future hardware releases.

   ∙ Avoid using interrupt vectors. If you must use them, use Setexc().