The $D700/$D7FF area

What is it?

Some info about the area $D700/D7FF in the memory map of the C64 and C128.

Soldering

Unfortunately you only can use this range by doing some soldering. And this can be a problem to some people. For the C128 you have to solder one line on the board. For C64 you have to piggyback another 74LS139 to the original one. Cut the line between this 139 and the SID and connect the ends to the chipselect (pin 1) and output Y0 (4). Connect the select-inputs A and B (2 and 3) to the addresslines A8 and A9. Connect the inputs 13..15 to 16.
For those people who have the newer, smaller board with the 85xx chipset, You won't find a 74LS139 on it, so you have to use another one as carrier. (At this moment I cannot give you any advise, sorry)

Software compatibility

"Will I have problems with the software I'm using now?" For a C128 in native mode: 100% NO!. The only trouble we could run into using a C64 or a C128 in 64-mode is with software using mirror-addresses for reading or writing data. But this software would not work on the C128 either as this area is not used on this machine. Until now I haven't found or heard of any program using these mirror-addresses.

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