Address mirroring on 128K/512K/Plus — #11

Post #11 by bigmessowires

Source Forum	68kMLA
Category	68k
Post Date	Sat, 10 Sep 2011 - 17:18
Original URL	https://68kmla.org/bb/threads/address-mirroring-on-128k-512k-plus.23825/

Post

Awesome! OK, I really need to get that book.

You can see the answer to my original question in the footnote on the Plus memory map diagram:

Note: 128 KB ROMs are disabled (no device assigned) everywhere A17=1.

So for a 512Ke, $020000-$03FFFF maps to a copy of the ROM, but on the Plus, that same address range is not mapped to anything.