(c)  Copyright 1989-1999 Amiga, Inc.   All rights reserved.
The information contained herein is subject to change without notice, and 
is provided "as is" without warranty of any kind, either expressed or implied.  
The entire risk as to the use of this information is assumed by the user.


                       
                        PAL and NTSC Differences

                          by Carolyn Scheppner


                               HARDWARE

The parts list below has been updated to include NTSC and PAL components for
the 2-layer A2000.  Members of the Developer Support Program located in the
U.S. may order PAL parts from CATS (for more information, call the CATS
number listed on your Hardware Price list).  Overseas developers should check
with their local Commodore office for NTSC parts availability.

     
                                     4-Layer                   2-Layer
                         A1000        A2000        A500         A2000

AGNUS    NTSC part#    252125-01    252125-01    318070-01    318070-01  
         PAL  part#    252362-01    252362-01    318071-01    318071-01 

CRYSTAL  NTSC part#    325566-14    325566-12    325566-14    325566-12       
         PAL  part#    252344-01    252344-01    252344-01    252344-01

POWER    110V USA      327173-01    internal     312503-01    internal
         240V BSI            -02     jumper            -02     jumper
         220V VDE            -03    on power           -03    on power
         220V SEV            -04     supply            -04     supply




Note: the Enhanced Chip Set, which includes a 1 MG Agnus chip, will allow
external switching between PAL and NTSC video modes on the 2-layer A2000.




                             SOFTWARE

There are some software differences that you should keep in mind while 
developing products for the international market:

   - Many international keyboards have different RAWKEY codes from
     the US keyboard.  Use CON: or console.device for automatic
     translation to the correct ASCII values.

   - Define your char variables and arrays as UBYTE.  This will prevent
     sign extension on 8-bit ascii international characters.  Test all
     of your text input routines with international characters.
     You can type international characters.  You can type international
     characters on a US keyboard by using the deadkeys (for example, ALT/K 
     then O will make an O with an umlaut accent).

   - PAL screens have more lines (256, 512 interlace).  Use the 1.2
     Intuition GetScreenData function to get a copy of the Workbench Screen 
     structure, or check Gfx->NormalDisplayRows which contains the height
     used for a non-interlaced Workbench screen.  Be careful when doing 
     any low level graphics programming based on the beam counter.
     Remember the counter will go higher on a PAL machine.

   - When using a clock constant in audio period-to-frequency 
     calculations, remember that a different clock constant must be
     used on PAL machines.  Check GfxBase->DisplayFlags to see if
     you are running on a PAL machine.  The NTSC clock constant is
     3.579545 MHz.  The PAL constant is 3.546895 MHz.