The VIC-20 ships with 5K of RAM. Adding a memory cartridge fills $0400–$0fff and $2000–$7fff, which moves the BASIC program start and the screen, so an unexpanded layout and an expanded one differ. The $ff81–$fff5 KERNAL jump table matches the rest of the Commodore 8-bit line. See also the
C64 memory map and
PET memory map.