Re: Question on ProDOS SmartPort drive remapping

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

David Wilson <mcs6502@gmail.com> wrote:

> On Dec 5, 8:51 pm, "BluPhoenyx" <bluphoe...@a2central.com.remove-i9j-
> this> wrote:
> > David Wilson wrote:
> > > ProDOS supports up to 14 volumes but reserves 3/2 for /RAM (v2.0.1
> > > forgot to do that and would, if you had enough SmartPort devices, map
> > > a drive to it and then overwrite it with /RAM). I have managed to get
> > > 15 drives working under ProDOS by using 0/2 (0/1 aka Unit 00 is
> > > special and cannot be used).
> >
> > Is it possible to disable the /ram to allow another disk to be remapped?
> 
> It might be possible. I would have to find the size of the table used
> to map ProDOS unit numbers to SmartPort slot and unit numbers.

The big problem with disabling /RAM permanently is that it is
intricately involved in the mechanism for using auxiliary memory.

If /RAM is present when an application is launched, it can be used to
reserve certain areas of auxiliary memory (e.g. video buffers), or the
application can disable /RAM and have almost complete access to
auxiliary memory.

If /RAM is not present when an application is launched, there are
different rules for which areas of auxiliary memory are available, on
the assumption that a system patch had to remove /RAM and is now
resident in the reserved areas.

Some applications will refuse to run unless /RAM is present when they
are launched, because they need all of auxiliary memory.

-- 
David Empson
dempson@actrix.gen.nz