(c)  Copyright 1989 Commodore-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.



                 Official Warning to ROM-Jumpers, 
                  Structure-Hackers, and Others

                   from Commodore Engineering, 
                    Commodore-Amiga and CATS



 We who bring you the Amiga want to make it perfectly clear that if you 
don't follow the rules, your code WILL break.  To that end, we present the 
following Amiga commandments.



Do NOT jump directly into ROM code
----------------------------------
 
     Do not jump into ROM.  Beware of any example code that calls routines
in the $F80000 to $FFFFFF range.  Those are ROM addresses and those ROM
routines WILL move.   The only supported interface to system ROM code
is through the provided library, device, and resource calls. 

     

Do NOT modify or depend on private system structures 
----------------------------------------------------
 
     Do not modify or depend on the format of the private system structures.
This includes the poking of copper lists, memory lists, and library bases.


      
Do NOT depend on the addresses of 
system structures or free memory
----------------------------------

     Do not depend on any address containing any particular system structure 
or type of memory.  The system modules dynamically allocate their memory
space when they are initialized.  The addresses of system structures and 
buffers differ with every OS, every model, and every configuration, as
does the amount of free memory and system stack usage. 



Do NOT depend on a certain proceesor or clock speed
---------------------------------------------------

     Do not use assembler instructions which are priviledged on any 
68000 family processor.  All addresses must be 32 bits.  Do not use
the upper 8 bits for other data.  And do not execute code on your stack 
or put system structures on your stack.  Do not use software timimg
loops or delays.  Do not use the TAS instruction.  Do not use self-
modifying code.
 
Do NOT ignore software interfacing specifications
-------------------------------------------------

     If you are using the system libraries, devices, and resources, you
must follow the defined interface.  Assembler programmers (and compiler
writers) must enter functions through the library base jump tables,
with arguments passed as longs and library base address in A6.  Results
returned in D0 must be tested, and the contents of D0-D1/A0-A1 must be 
assumed gone after a system call.


 
Do NOT ignore hardware interfacing specifications
-------------------------------------------------

     If you are programming at the hardware level, you must follow hardware
interfacing specifications.  All hardware is NOT the same.  Do not assume 
that low level hacks for speed or copy protection will work on all drives, 
or all keyboards, or all systems, or future systems.  



     Software distributers who purchase or contract software from outside 
programmers must make sure that the programmers are aware of correct 
programming practices and are providing software which will not break on 
different machines or different OS revisions.

     We are dedicated to enhancing and expanding the capabilities of
the Amiga hardware and software, while maintaining compatibility
wherever possible for those who follow the rules.  Those who don't
follow the rules can consider themselves warned.




   


