CMNT	 	Input: É ¥ target/old value/incr/É
CMNT	 	Output:  É ¥ output/É
PRIM	Stack/Xover
PRIM	Stack/Xover
PRIM	Stack/Xover	target/ramp/incr/target/ramp/incr/É
PRIM	Value/Subtract
PRIM	Value/Absolute
PRIM	Value/Subtract	incr-abs(ramp-target)/target/ramp/incr/É
PRIM	Value/Test negative
BRFL	 	branch if delta less than incr.
	PRIM	Stack/Drop
	PRIM	Stack/Xdrop
	PRIM	Stack/Xdrop	return target if abs(target-ramp)<incr
BRTR
PRIM	Stack/Drop	target/ramp/incr/É
PRIM	Value/Compare
BRFL	 	branch if target >= current value
	PRIM	Value/Add	retrun ramp+incr
BRTR
PRIM	Value/Difference	return ramp-incr