Re: Upgrading the Apple][ to //e

[mjmahon@aol.com (Michael J. Mahon)]

David Empson wrote:

<snip>

>There are some other minor details, such as the self-test code in the
>$C100-$C7FF area

David, it is a rare day when I find an inaccuracy in one of your
posts--I consider them the gold standard--but I just happen to
be looking carefully at this very topic this week!  (I'm planning
some ROM additions.  ;-)

In the unenhanced //e, the self test code is in $C401..$C7FF.
Contrary to what the Reference Manual says, the $C100..
$C2FF region is dispatching code and additional 80-column
code.

In the enhanced //e, it is compressed to reside in $C600..$C7FF.
It is not only smaller, but also tests the AUX RAM if it is present.
This ROM also has cassette I/O and Applesoft tape interface
code in $C500..$C5FF.

Since I'd like to use three pages for my code (without modifications
I'd rather not make), and since in my configuration the additional
features of the enhanced ROM are unnecessary, I've decided
to use the unenhanced ROM as the base for my additions.

(BTW, does anyone know where I can find a source listing
of the unenhanced //e ROM?)

-michael

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