Just ran across a Windows emulator for the HP-16 calculator (if you want an RPN calc instead of AOS, this is neat Besides, it does hex, binary and octal calculations.) It's freeware. http://www.teleport.com/~dgh/hpsim.htm#wrpn This is part of the HP calculator museum, which has all kinds of keen stuff, including shots of old slide rules. It's at http://www.teleport.com/~dgh/hpmuseum.html