Memory Map -> RAM Contents -> $0000-$007f "completely unused"

[bobbyjim]

Of course that's no longer true, since $02 through $21 hold the 16-bit pseudo-registers used by the KERNAL ABI.

[PeterCamilleri]

So if I understand correctly, the free zero page is now

$00, $01, $22 .. $7F

Yikes! Not cricket!

[bobbyjim]

I think now that $00 and $01 will-be reserved for banking, and $02-$21 are used by the ABI but could perhaps be re-used.

[PeterCamilleri]

The C64 used those addresses for banking. AFAIK, the X16 is using a VIA chip in the I/O region to control bank switching.

[indigodarkwolf]

In the official emulator release r37, ROM and RAM banks are controlled by I/O registers $9F60 and $9F61, respectively.

However, the technical design of the X16 has changed and the ROM and RAM banks will be moved to zero-page registers $00 and $01, respectively. The documentation has already been updated to reflect this, emulator release r38 will contain this update as well.