Conversation so far:
how much time is given in a chess tournament
International chess has a standard time control of 40 moves in 2 hours and then an extra hour to reach move 60.
What instrument is used to measure time in chess tournament?
Chess clocks are used in chess and other two-player games where the players move in turn.
When the chess clock first used in a tournament?
The first time that game clocks were used in a chess tournament was in the London 1883 tournament.
Have chess clocks been improved from their beginnings?
In 1973, to address issues with analog clocks, Bruce Cheney, a Cornell University student, created the first digital chess clock as a project for an undergraduate EE course.

Question: How does the machine work?
Self-contained rewrite: How did the first digital chess clock work?