Quiz submission record for quiz4-1-2 at Mon Jul 12 20:51:03 2004:

Your Answer for Question 1:
The circuit should will not behave as expected if the flip-flops are linked circularly, which is to rorate the values in both flip-flops, although logic seems to suggest that it should.  When the first latch is open, the value of D is stored in the Q of the first latch of the first flip-flop.  After the latch is closed, it goes to the slave, which then has the input of D.  After the clock changes again, this signal is passed to the second flip-flop, and so on.  Even if both flip-flops were initialized with different values, this should still work, as the stored values should only be changing on the edges of the clock cycles, and the fact that there is both a master and a slave latch should cause the two flip-flops to repeatedly trade values.  However, the key problem is that if both flip-flops are connected circularly, there is no place for the initial signal to come from.

If the flip-flops are not linked circularly, I think that it should function as planned.  From the initial signal, the first flip-flop will take that value, and then pass it to the next flip-flop.  On the next clock cycle, a new signal could change the value stored in the master latch of the first flip-flop, but the output signal that was carried by the slave flip-flop will still be the original one, which will pass it to the next flip-flop.  So, the signal will travel down the flip-flops, with a cycle delay between them.

Your Answer for Question 2:
FSM are used in any situation where the situation is defined by the currently stored values and the input.  One could be the idea of electronic locks, like the card-keys in Soda.  Access is determined both on the state (which day it is, what time of day) and on the input (whether the person using the cardkey has access).  A second example could be the idea of automatic doors for supermarkets.  Obviously, it depends on the state of whether the supermarket is open, but also on the input of someone entering the path of the motion sensor.  A third example is taking showers in places in the middle of nowhere.  You can only get hot water if the state is that the water heater is on, and if your input has the faucet open.


Your unique submission ID is quiz4-1-2-cs61c-el-1089690663-2922.