S.Elliott's blog

Did you ever want to test whether there are any active bits at an unknown address or memory-mapped-IO port?  This one-liner uses vaporlock to distinguish active bits vs floating bits on the Apple data bus.

This precisely-timed machine code tricks a 2513 character generator into displaying a dancing-box at the current cursor position, despite the fact that the character generator contains only 64 character shapes -- none of which is a box-shape!