4hp Comparator
Compares two input voltages (A,B) with adjustable gap (how much voltages can differ and still recognized as "A=B") and makes appropriate output gates: A>B, A(lessthan)B, A(notequal)B, A=B.
Inputs are normalled to ground so you can compare one input voltage with gnd.
http://ladik.ladik.eu/?page_id=1459
No info about availability.
$47