A stopwatch is a timepiece that measures the amount of time between any two occurrences. Usually, at the first occurrence, the stopwatch is started while at the second it is stopped. To use it again, a reset option is also provided with the stopwatch. The total time elapsed can thus be obtained. A stopwatch is very commonly used in racing competitions and other gaming activities. The circuit given here is a digital stopwatch that displays time on four seven segment displays using 8051 microcontroller (AT89C51) .