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What is the forbidden state of an SR latch?
A forbidden state in this case means that the output is non deterministic, i.e. unknown. An unknown state is typically drawn as two parallel lines (meaning it could be at either level). Here are the various states, I’ve used a NAND based latch and inverted the inputs or ease of understanding.
What is reset in SR latch?
The simplest bistable device, therefore, is known as a set-reset, or S-R, latch. To create an S-R latch, we can wire two NOR gates in such a way that the output of one feeds back to the input of another, and vice versa, like this: The Q and not-Q outputs are supposed to be in opposite states.
What happens when s goes back to 0 on a latch?
Similarly, if S goes back to 0, then the circuit will remain in the set state, i.e. S=0 and R=0 is the memory or hold state which means latch is holding or storing the previous output.
How does an SR latch ” get started “?
You make the latch “get started” by setting one of the inputs (R or S) to be a 1 while the other input is a 0. This will force the latch into a known state, regardless of whatever the previous state of the latch might be.
Which is the stable state of a Rs latch?
An RS latch has a stable Q high state and a stable !Q high state, but it also has an essentially infinite number of metastable states. When the latch is in a metastable state, the outputs may arbitrarily switch high and low for an arbitrary length of time, though in practice most metastable states fairly quickly resolve into a stable state.
Which is the correct diagram for S-R latch timing?
Diagram #1: S = R = 1, gives you BOTH Q and /Q as being asserted, whereas by definition they should be complimentary to each other. However, if you take the meaning of SET to be to assert the Q state, and you take the RESET to mean to assert the /Q state, the SET and RESET are actually doing their jobs.