Save money, learn Ratio Deco
here instead . . .not only is it more useful and easy to implement in your head at depth during a contingency where you have to recalculate your Deco Profile on-the-fly; but it's easy to pre-plan or re-plan a profile in certain circumstances where having laptop or PDA Deco Software is not practical (i.e. in a small outrigger bangka diveboat off the Luzon Philippine Coast during a rain squall in the South China Sea). . .