[frobozz]

I wouldn't trust these programs to work. The fibonacci one certainly doesn't.

When the explanatory line in the fibonacci example first hits the left hand side of the program, the Direction Pointer appears to be being rotated anti-clockwise.

Were it rotated clockwise, as-per the spec, it would go up, hit the black block above, and eventually end up in an infinite loop.

The command executed on entry to that block is PUSH (pale to normal yellow), so it shouldn't have any effect on DP.