Obsbedia2 <obsbedia2@aol.com> wrote:

> << In theory, GS/OS could have eventually supported all the built-in
> peripherals and all the slots at the same time, as Apple had designed a
> "slot arbiter" mechanism. >>
> 
> "slot arbiter?"

The slot arbiter is a component of GS/OS (in System 4.0 and later), and
is also included in the ROM for a ROM 3 IIgs.

Its purpose is to manage (arbitrate) the use of the slots and the
built-in I/O features which correspond to the slots.

If it was fully supported, it would operate by dynamically switching
between the real slots and the built-in I/O as required by GS/OS device
drivers.

For example, you could install a disk controller card in slot 5, and use
any drives connected to that card as well continuing to use the built-in
disk port (which is also mapped to slot 5).  This would have only been
available in GS/OS applications - when switching to ProDOS-8, the
control panel settings would determine whether the internal I/O device
or the slot was active, as normal.

As I said in my previous message, the slot arbiter was never fully
implemented, or at least it wasn't fully used by GS/OS, probably because
too many I/O cards, drivers and/or applications were assuming the slot
assignments would not change on the fly.

-- 
David Empson
dempson@actrix.gen.nz