 The personal decompression computer provides a real time modelling of the inert gas load on the diver according to the decompression algorithm programmed into the computer by the manufacturer, with possible personal adjustments for conservatism and altitude set by the user.In all cases the computer monitors the depth and elapsed time of the dive, and many allow user input specifying the gas mixture.Most computers require the diver to specify the mixture before the dive, but some allow the choice of mixture to be changed during the dive, which allows for the use of gas switching for accelerated decompression.