Re: Apple /// Help?

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

In article <445a0g$f0a@Mercury.mcs.com>, Greg Linder <fluke@MCS.COM> wrote:
> 	I have come into possession of an Apple ///, without manuals or any
> type of monitor. I can get into the debugger, but it refuses to boot
> Prodos 1.1 or Dos 3.3. Does the apple /// need a different dos?

Yes.  The Apple III has its own native operating system called SOS
(Superior Operating System).  This uses the same file system as
ProDOS, but the applications are not interchangeable.  Most data files
are compatible, e.g. the Apple III program "/// Easy Pieces" is
the original version of AppleWorks, and is fully compatible with
AppleWorks 1.x files.

To run Apple II software, you need the special Apple II emulation
disk, which loads necessary software and puts the III into a special
hardware emulation mode in which it can act like a 48K Apple II+ (no
language card, but you can select whether Integer or Applesoft BASIC
is available).

In this mode, you should be able to use much old DOS 3.3 software, but
not anything which requires 64K or a IIe or a later machine.

ProDOS 1.0 and 1.0.1 will work in the Apple II emulation mode on an
Apple III, but most ProDOS applications will not work in 48K (the
operating system sits where BASIC.SYSTEM normally lives).  ProDOS 1.1
and later require 64K, so cannot be used.

There is a third-party Apple IIe emulation card for the Apple III
which gives you a 128K IIe, I think.


The Apple III contains practically no ROM.  All it has is a very
rudimentary debugger and enough code to boot from the internal 5.25"
drive.  All device support (keyboard, video, serial port, joystick,
printer port, disk drives, ProFile, other add-on devices, etc.) is
provided by device drivers loaded from the SOS boot disk, which must
be installed as required.

There is no built-in language in the ROM (e.g. BASIC), but there is a
very good BASIC implementation ("Business BASIC") which is a SOS
application.  There is also an Apple III version of Pascal which is
very similar to Apple II Pascal (but it uses the SOS file system and
has access to much more memory than Apple II Pascal).

> Will it work with a GS monitor?

It might appear to work (I know of one person who has done it, with
problems), but I wouldn't recommend it.  The Apple III expects a
digital RGB monitor (same type as most IIe RGB cards or for the IIc via
an adaptor, or a CGA digital RGB monitor with an appropriate adaptor),
whereas the IIgs monitor is analog RGB.

A custom cable would be required at the very least, and the voltages
produced by the Apple III video circuitry might be out of the valid
range for the IIgs monitor.  The colours displayed are wrong.

It should be possible to build an adaptor to allow a IIgs monitor to
be used with an Apple III.  There is a circuit shown in the III
Owner's Guide showing a typical circuit (mostly resistors).

> Where might I get a tech manual for it?

I don't think there is a technical manual for the Apple III.  It was
a much more "closed" machine than the Apple II, and very little was
released by Apple in the way of technical documentation.  There might
be third-party books that fill the gap.

The Apple III Owners' manual and SOS manuals contain enough technical
information to whet your appetite, but don't go into much low-level
detail.

(I have a few Apple III manuals, but I've only briefly seen the actual
machine.)
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand