** Program location
Defaults to $801 for ROM-based Applesoft. Locations $67/$68 point to
the start of the program, and the byte preceding it must be #0.

Details:
- http://www.atarimagazines.com/compute/issue11/36_1_THE_APPLE_GAZETTE_RESOLVING_APPLESOFT_AND_HIRES_GRAPHICS_MEMORY_CONFLICTS.php
- http://retrocomputing.stackexchange.com/questions/1604

** Format
DOS stores an additional byte on the end, which should be ignored.