How Can a D-Type Flip Flop Handle Simultaneous High Inputs?

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SUMMARY

The discussion focuses on the behavior of a D-Type Flip Flop when both SET and RESET inputs are simultaneously high (SET = RESET = 1). In this scenario, the RS NAND latch can yield two potential outputs: Q = 0 and Q(not) = 1, or Q = 1 and Q(not) = 0. The output state depends on the previous conditions of the inputs, leading to uncertainty in the output until the circuit stabilizes. This highlights the importance of understanding the timing and sequence of input signals in digital circuits.

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http://img329.imageshack.us/my.php?image=39501432oa1.jpg

if one of them was 0 then no problem because the other wire value doesn't matter
but here we have both 1
if i look on one of the NANDs gates we have one input of 1
and the other input value is unknown because it comes from the resolt of the other gate
which has the same problem

how to solve it??
 
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When SET = RESET = 1, there are two likely outputs of our RS NAND latch. We can have Q = 0 and Q(not) = 1. In this case, the input to the lower NAND gate is 0 and 1, which gives Q(not) = 1. The inputs to the first NAND are both 1 which makes Q = 0.

The second possibility is to have Q = 1 and Q(not) = 0. The same analysis used above can be applied for this situation.

So which situation occurs first? This depends on what has occurred previously at the inputs.
 

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