Anyone know of a good source that describes how RAM and ROM are mirrored at different addresses on the Mac 128K, 512K, and Plus? I remember reading something about it a few weeks ago, possibly here, but can't find it now.
I'm not talking about the basic memory map, which is well documented, but the details of where mirrors of RAM/ROM appear elsewhere in the memory map besides their regular locations. For example, the 128K ROM on the Plus is at $400000-$41FFFF, but is probably also mirrored at $420000-$43FFFF, among other places.
I think I also read something here on this site that mentioned that the presence/absence of particular mirroring windows was used by the boot ROM to detect how much memory is installed, or whether a machine is a 512Ke or a Plus, or something like that.
I'm not talking about the basic memory map, which is well documented, but the details of where mirrors of RAM/ROM appear elsewhere in the memory map besides their regular locations. For example, the 128K ROM on the Plus is at $400000-$41FFFF, but is probably also mirrored at $420000-$43FFFF, among other places.
I think I also read something here on this site that mentioned that the presence/absence of particular mirroring windows was used by the boot ROM to detect how much memory is installed, or whether a machine is a 512Ke or a Plus, or something like that.