Re: 6 & 2 / 5 & 3 Encoding

[david@wraith.cs.uow.edu.au (David E A Wilson)]

Steve Leahy <Steve.Leahy@anu.edu.au> writes:
>david@wraith.cs.uow.edu.au (David E A Wilson) wrote:
>> the other a simple test stub to see what happens
>> when P8 v2.0.1 has 14 volumes and tries to add /RAM).

>Enlighten us. How does P8 2.0.1 cope with it?

Badly (that is why P8 v2.0.3 was released). It adds BF to the end of the list
of active devices which ends up outside the array space allocated to it in the
global page. It also installs the vector for the /RAM driver overwriting the
previous slot 3 drive 2 contents. Thus you still only have 14 devices but
slot 3 drive 2 appears twice in the list of active drives.

Of course if Apple had left /RAM in slot 0 drive 2 as was documented in the
first release of the ProDOS Technical manual then we would not have had quite
the same problem (it would still be possible to have 15 devices overrunning
the active device array space).

P8 v2.0.3 never mirrors a smartport device into slot 3 drive 2 so /RAM always
has a place to live (although what would happen if you put a disk controller
card in slot 3?).
-- 
David Wilson	Dept CompSci Uni Wollongong Australia	david@cs.uow.edu.au