The Dive Computer is based on a totally different concept than the tables; Thus, if with the tables the most important thing is to know the time that it takes to dive, for the computer the fundamental thing is to know the time that remains from it.
All computers work from algorithms, comparing their decompression model with the data obtained during the dive. Currently the most widely used algorithms are those of Bühlmann and Spencer, followed by those of Haldane, Rogers and Powell.
Thus, the computer bases its operation on capturing a large amount of data; such as the duration of the dive, its depth at all times and even the water temperature, from which it is used to calculate the saturation level reached by the diver’s tissues at all times. From this calculation, the device will calculate how long the diver can stay at that depth without the need for decompression or, if this is necessary, what stops he will have to make.
Obviously, the more data we give the computer, the more accurate the calculations it performs.