Re: Apple III

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <D2svxo.8GC@dorsai.org>,
James OReilly <joreilly@news.dorsai.org> wrote:
> 	I suppose it would be too optimistic to hope that Apple III 
> software ran on the Apple II and vice-versa?  Or had Apple not yet 
> developed technology so advanced that it was impossible to provide 
> backward compatibility?

It is possible to run Apple ][+ software on an Apple III, by using the
Apple ][+ emulator.  It emulates a 48k Apple ][+.

There is also a hardware card which allows a IIe to run Apple III
software.

Running native Apple III software on any Apple II is probably
impossible.  The Apple III has a special architecture which includes
extensions to the processor's addressing modes and instruction set.
There is no way this could be implemented on an Apple II without
hardware support, or software emulation of the Apple III, resulting in
very slow execution.

Then there is the small issue of the operating system.  ProDOS is a
subset of SOS, and I doubt the entry points and calls are the same.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand