1. Reaction timer (20 points) By changing the state machine from...

1.
Reaction timer (20 points)
By changing the state machine from lab 4, the stopwatch can be converted to a reaction timer. There are two button inputs: START-RESET and STOP. When START-RESET is pressed a light turns on and the stopwatch starts running. Then, when STOP is pressed the stopwatch stops, displaying the elapsed time between the pressing of the two buttons. A second pressing of START-RESET turns off the light and clears the stopwatch for another trial. If a "tester" operates the START-RESET button and a "subject" operates the STOP button, the stopwatch measures the subject's reaction time after seeing the light go on.
Write a state diagram for a modified state machine with these inputs, the same ENABLE and CLEAR outputs to control the counters, and also a LIGHT output.

2.
Reaction timer with fastest time display (20 points)
Add components to the reaction timer to also display for the fastest time (the "time to beat"). When the START-RESET button is pressed for the second time to clear the stopwatch, the fastest time is updated to show the minimum of the stopwatch time and the fastest time. In this way the fastest time always shows the best time so far. If START-RESET is pressed twice in succession without an intervening STOP, then both the current time and the fastest time will reset to zero.
Your solution will take the form of (a) a block diagram showing the original stopwatch / reaction timer with additional components, all signals labeled, to implement the fastest time display; and (b) a modified state diagram for the controller.

3. Two's Complement Arithmetic (10 points)
Complete the following operation using 8-bit signed numbers. Indicate if an overflow occurs
a) -128 + 127
b) -128 - 1
c) 10 - 14
d) 65 + 73
e) 65 - 73