limiting to "no less than" zero

[Darrel Taylor]

Darrels method using volume.15 is great, but it "wastes" half of a variable.
Most of the variables that I need to limit are declared as bytes, and I need the full 255 step range for some of them.

With 8-bit values, the CARRY flag is valid after addition or subtraction.

So it can be ...

if buttonB then
    Volume = Volume - Vstep
    IF !STATUS.0 THEN Volume = 0   ; Zero if BORROWED
endif