S5-P2 Flashcards
4
A
Note: At first the value 1 is stored in D, with the first rising edge clock, it transmits to Z.
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4
A
Note : Since we have a connecting line between input x and output z we know it’s Mealy. So Opt 2 is not the answer.
Note On Option 1: It’s eliminated at first, since the seq. of input x is 0 at the end and if input x is 0 then z is 0.
Note: state 00 is y1=0, y0=0 we input the seq.s in the option 4, and find the output.
2
A
Note: When Z is 0, if A and B are not both 1 then S is 0, and when S is 0, it doesn’t matter what R is, Z stays 0. Only opt. 2 has this.
Note On SR FlipFlops S=R=1: When both S (Set) and R (Reset) inputs of an SR flip-flop are set to 1, it can lead to an invalid state, which is also known as the “forbidden state” or “race condition.” In this state, both outputs of the flip-flop try to go to 0, which is not a stable configuration. As a result, it is impossible to predict which output will go to 1 and which will stay at 0. This condition violates the fact that both outputs of the SR flip-flop are complements of each other since each of them tries to go to 0.
1
A
It’s similar to Q15: You have the present state and the next one, use two K-maps each for one bit of the next state we’ll be in, in each k-map you have input x on one side and the current state on the other, values are the bits of the next state. write the formula according to the characteristic equation of the flip flops used.
The default order of a,b,c,d is the same as the order of K-map (00,01,11,10 even if the question hadn’t mentioned it.)
The states are g1g0 states
Note On Eliminating Opt 2,4: in state c (state g1g0=11) the output (z)=0, but in 2 and 4 opt.s Z is not 0.
Note: x is the number on the arrows, and in D flip flops, D=g(next), It’s important to note we write in this order g1g0 so for example in state b (g1g0=01), D1=1, D0=1 which is the next state (c), and x is 1 which is the input given by the clock to go to the next state. so we need to find the equation that satisfies this condition.
End Of P2
