Re: ROM

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

<bobryan9@my-deja.com> wrote:

> I have a ROM chip and I want to copy the $C8 ROM from it.  I figured I
> could just switch in it's $C8 rom and then BSAVE it, but it appears
> that the Disk II controller switches in its $C8 when you use the
> controller :).

The Disk ][ controller doesn't use the $C800-$CFFF space, but accessing
another slot might interfere with the card which is currently using this
space, depending on boundary accesses to adjacent slots and the precise
details of how each card implements this space.

> I would like to open a text file and save the source in it, I guess.
> Is there any other method for copying the area from $C800 to $CFFF?

Use a monitor command to copy it down to normal RAM.  If you've been
using the 80-column firmware, make sure you exit first using Escape
Ctrl-Q.

The following command sequence is your best shot:

]CALL-151
*8800<C800.CFFFM
*3D0G
]BSAVE C8.ROM,A$8800,L$800

This might not work either.  If so, the only way to access the code
reliably would be to write a machine code routine to copy the contents
of the $C800-$CFFF area directly.

Of course a moved copy of the code will be slightly messy to
disassemble, but outputting it to a text file then editing the output
should fix it.


Note that you might not be able to get valid contents for several bytes
at the end of the $CF page, depending on how tightly the card has
implemented the $CFFF address decoding.  For example, a card which only
needed 1KB of extra ROM space might disable this area for any access in
$CC00-$CFFF.

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