Best System for Apple II Software Compatibility

[great_hierophant@hotmail.com (Great Hierophant)]

I'm not sure the group got this post, so I am posting it again.

With Apple IIs, there are four major subfamilies of the machine, the Apple
II/II+, the Apple IIe/Enhanced IIe/Platinum IIe, the Apple IIc/IIc+, and the
Apple IIgs.  The Apple IIgs is required for all 16-bit Apple II software.  But
for 8-bit Apple II software, which Apple II model will offer the best
compatibility with the least headaches?

An Apple II/II+ will not run some later software, no matter how much extra RAM is
installed in the machine.  It probably won't even run Prodos.  An Apple IIc/IIC+
has not enough room for expansion slots, and any expansion seems more trouble
then its worth.  I doubt that there are many programs that will only run on an
Apple IIc.  This leaves two choices, an Apple IIe and an Apple IIgs.

An Apple IIe seems like the best choice.  It would be best to get a Platinum IIe
if possible because they were the latest model and has only cosmetic differences
between an Enhanced IIe.  (A non-Enahnced IIe and an Enhanced IIe may be
difficult to tell apart in a poor photo.)  All Platinum IIe machines come with
extended 80-column cards, ensuring support for 80-column text, double low
resolution, double high resolution graphic modes, and any program that requires
128KB of RAM.  They also usually come with 5.25 disk controllers and super serial
cards.  It also has all the standard Apple II ports, including the audio ports
for casettes, the game I/O connector, a composite video out.  The CPU will also
be a 65C02 in case any software uses the extra instructions.  The Platinum model
also has a convenient numeric keypad attached.

But consider the Apple IIgs's charms.  Not only does it run 16-bit software, uses
a mouse as standard, has a GUI OS, usually comes with 800KB disk drives, comes
with Prodos as standard, and there is only one model to worry about.  (ROM 01 is
supposed to be the most compatible of the firmware.)  It has most of the Apple
II's functionality, including all the external ports except the audio outs for
casette storage.  This means that software on tape and programs that use the
casette port for audio output will not work.  What other incompatibilities does
this system have? Certain slot perihperals for 8-bit Apple IIs may not work in
the more restrictive Apple IIgs slots.  Software that tweaks the Apple II speaker
may not sound correct because the Apple IIgs uses the Esoniq chip to emulate it.
Software that uses firmware routines in the 8-bit Apple II's may not work because
the routines no longer exist or do not function the same.  Can the Apple IIgs's
video hardware drive a composite monitor in the same way as earlier Apples?  Do
design differences in the IIgs's 65816 break programs that use 6502 instructions?

GH