Re: Apple IIc plus

[mdj <mdj.mdj@gmail.com>]

On Aug 22, 11:53 am, mdj <mdj....@gmail.com> wrote:
> On Aug 21, 5:28 am, "mre...@gmail.com" <mre...@gmail.com> wrote:
>
> > Now my questions:
> > * Does somebody know if $CE00-$CFFF is the correct memory range?
> > * Are there any other RAM memory areas in the $C000-$FFFF ROM address
> > space?
> > * Is it shared with some of the main or language card memory, or is it
> > stand-alone memory?
> > * Is it non-volatile RAM?
>
> That RAM is used as a track buffer for reading and writing 3.5" disks.
> If memory serves, it's 2KB, and was more than likely SRAM.

If you don't get any other leads, I'd try this:

An access to $C5xx *probably* enables the RAM chunk at $C800-$CFFF. An
access to $CFFF would disable it.

That range is the "extended firmware space" on the Apple II. A card in
any slot is free to use it. The $CFFF protocol is the established way
that all cards relinquish use of the space, and an access to your
cards firmware space is the green-light to activate address decoding
in that area. Have a look through the firmware for a dummy access to
$CFFF - that might provide all the info you need.

Cheers,

Matt