Hi: Yes, it's what made HP as a company. http://www.hp.com/hpinfo/abouthp/histnfacts/museum/earlyinstruments/0002/ https://www.google.com/patents/US2268872 -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html The lesser of evils is still evil.