There's an open-source clone of the HP-42s that has found it's way into different smartphone apps. I use Free42 for iOS and it works beautifully. Plus I can l

There's an open-source clone of the HP-42s that has found it's way into different smartphone apps. I use Free42 for iOS and it works beautifully. Plus I can leave my real 42s safe in a drawer at home. https://itunes.apple.com/us/app/free42/id337692629 https://itunes.apple.com/us/app/free42/id337692629 There are other builds for Android, Windows, Mac, and Linux: http://thomasokken.com/free42/ http://thomasokken.com/free42/