Re: HD, ProDOS, & GS/OS

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

James OReilly <joreilly@smtp.dorsai.org> wrote:

> If I decide to get a hard disk and install GS/OS System 6.0.1 (I believe
> that's the lastest (& last?) version)

Yes, it is.

> on it, can I still boot ProDOS programs from the floppy drive?

It depends.

The main thing that controls what will boot is the order in which disk
controllers (or devices that look like disk controllers to the boot
firmware) are installed in slots.

In the default setting (startup slot set to "Scan"), the IIgs will start
at slot 7 and search down the slots until it finds a bootable device
with a valid boot disk.  Changing the startup slot just specifies where
to start scanning (skipping higher numbered slots).

(I'm assuming you don't have any old devices that don't know to resume
booting after a timeout, such as a UniDisk 5.25 or Disk ][ controller
card.)

If your SCSI card (or Focus, or whatever) is in slot 7, then you will
always boot from the hard drive.  (Unless you change your startup slot,
which is fiddly.)

On the other hand, if your hard disk controller was in slot 1, 2 or 4,
then your system would try booting slot 7 (presumably empty), then 6
(5.25" drive, if enabled), then 5 (3.5" drive), then the hard drive.
Any drive without a bootable disk would be skipped (the 5.25" drive is
pretty slow, and if you rarely boot from it you should set the startup
slot to 5 in this configuration).

The problem is that you might not be able to use slot 1, 2 or 4 for your
hard disk controller, because their built-in function is probably
required (printer, modem, mouse).

Read on, however.  All is not lost...

> I ask this question, because I understand that although one can choose
> ProDOS under GS/OS, certain applications have problems running under the
> GS/OS implementation of ProDOS.

There are two possible issues here:

1. The program doesn't like running under ProDOS-8 if you boot the
system via GS/OS.  This may be due to additional software loaded by
GS/OS during its boot process (more overheads), less memory available,
or whatever.

2. The program doesn't like running under the specific version of
ProDOS-8 that is used by System 6.0.1 (namely ProDOS-8 2.0.3).  I don't
know of anything significant which would be affected by this.

Issue 1 can be avoided by booting directly into ProDOS-8.  With System
6.0.1, you can press the '8' key at boot time to go directly into
ProDOS-8, bypassing GS/OS completely.  (The timing can be a little
fiddly - wait until the hard drive starts to be accessed, but you have
to press it before the graphical "Welcome to the IIgs" screen appears.)

With a default installation, using this method will drop you into
BASIC.SYSTEM, and you can type BYE to get back to the ProDOS-8 program
selector, from which you can launch any ProDOS-8 application (SYS file)
you like, on any mounted volume (including floppies).

Alternatively you could install a third-party program selector as the
first .SYSTEM file in your root directory, and you would boot straight
into that program.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand