Re: More than 4 drives on a daisy-chain?--Maybe!

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

Obsbedia2 <obsbedia2@aol.com> wrote:

> << Finally there is a limit imposed by the operating system.  ProDOS-8 can
> only have 14 units in total, spread over all slots, including /RAM
> (leaving you with a limit of 13 real volumes).  >>
> 
> Thank you for the run down.
> 
> Is the above actually the OS or a firmware limitation?

Primarily an OS limitation, imposed by the unit numbering scheme.  Bit 7
is the drive number (0 or 1), bits 4-6 are the slot number (1 to 7; 0 is
reserved).  Bits 0 to 3 are not available, because they are used for
other purposes.

> I've see the prototype for the 10 Slot Apple II+.

I can't see how that would work.  There isn't any space left in the
memory map for more slots.

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