This is a game for two players.
Player 1 presses the START button. This resets the 4026 counter chip and starts the
555 oscillator.
The 555 produces 10 pulses per second and these are counted by the 4026 chip and
displayed on the 7-Segment display.
The second player is required to press the STOP button. This freezes the display by
activating the Clock Inhibit line of the 4026 (pin 2).
Two time-delay circuits are included. The first activates the 555 by charging a 10u
electrolytic and at the same time delivering a (high) pulse to the 4026 chip to reset it.
The second timer freezes the count on the display (by raising the voltage on pin 2) so
it can be read