Memory Organization:
An Apple III operating SOS or Pascal has different memory organization than
when running Apple II Pascal. The amount of memory available is somewhat
greater on the 128K Apple III than on the Apple II.
Memory organization could effect an Apple II program run on a Apple III, if
the program depends on pointer values created when running on an Apple II and
stored on a diskette.
Similarly, an Apple II program that depends on specific Apple II hardware
addresses does not work on the Apple III. This could for example affect
Apple II Pascal programs designed to drive the Silentype printer; though such
programs could be revised to use the Apple III Silentype driver described in
the Standard Device Drivers Handbook.
The UNITSTATUS Procedure:
The UNITSTATUS procedure is supported for device oriented I/O. See Chapter
12 of the Apple III Pascal Programmer's Manual.
Runtime Segment Table:
The runtime segment table allows for 64 segments instead of 32. See Chapter
15 of the Apple III Pascal Programmer's Manual.
Conditional Compiling:
The Apple III Pascal Compiler allows conditional compilation. See Appendix F
of the Apple III Pascal Programmer's Manual.
CHAINSTUFF Unit:
Since Apple III Pascal has no "system swapping" mode, the SWAPON and SWAPOFF
procedures are absent from the CHAINSTUFF unit.
Compiling Apple II Code:
The Pascal III compiler can compile code to run on the Apple II. Refer to
Appendix F of the Apple III Pascal Programmer's Manual.
File Variable Size:
Every declared file in an active procedure requires 1,100 bytes of memory.
Compiler Options:
Option names can be spelled out.
Because Compiler options always end with a comma, all can be chained together
except for the Include option. The Comment option cannot contain a comma and
the Resident option does not accept a list.
Procedure Complexity:
The Apple III larger memory supports more complex code than the Apple II.
System Globals:
Users of the {$USER-} option may find that their programs are not portable.