Abstract: A small electronic device having a depth gauge is provided. An electronic device includes a pressure sensor which produces a signal corresponding to a depth. A first memory stores decompression data while a second memory stores residual nitrogen time. The first counter counts a dive time while a second counter counts a surface interval time. A calculating circuit calculates non-decompression time limits based upon the depth information and decompression data. A decompression management circuit determines when the decompression time limit has exceed and calculates the decompression dot profile and output decompression dive data. A second calculating circuit calculates repetitive dive non-decompression time limits based upon the previous the dive depth, dive time interval surface time interval and the residual nitrogen time. The control circuit receives each bit of information and causes a displayed display information either simultaneously or independently.