Mappings and pagetables

One of the major improvements over the ZX Spectrum version of Nixy 2 is the inclusion of a map. It even shows an overview of how each screen looks like! 

The visited screens are shown in dark grey, the current screen in green and the unexplored areas in light grey. 

The map uses its own tile set (64 tiles). The game switches from the main display at $f800 to the map display at $0400 and back, switching the tile-set accordingly. The game loop is paused while the map is open.