## Which state is invalid in SR NAND latch?

For a NAND gate latch both inputs LOW turns ON both output LEDs. Having both S and R equal to 0 is called an invalid or illegal state for the S-R Latch. Otherwise, making S=1 and R=0 “sets” the multivibrator so that Q LED is ON and !

## What is invalid state for SR latch?

SR latch is a gated set-reset latch. The S and R inputs control the state of the latch when a HIGH level is applied to the EN input. The latch does not change until EN is HIGH. An invalid state occurs when both S and R are HIGH.

What does illegal state mean in latches?

A bistable multivibrator has two stable states, as indicated by the prefix bi in its name. For this reason, having both S and R equal to 1 is called an invalid or illegal state for the S-R multivibrator. Otherwise, making S=1 and R=0 “sets” the multivibrator so that Q=1 and not-Q=0.

What input state must be avoided when using a NAND gate SR latch explain?

Because the NAND inputs must normally be logic 1 to avoid affecting the latching action, the inputs are considered to be inverted in this circuit (or active low). The circuit uses feedback to “remember” and retain its logical state even after the controlling input signals have changed.

### What is the difference between the NAND and NOR implementations of an SR latch?

From the truth table, we see that the main difference between this implementation and the NAND implementation is that for the NOR implementation, the S and R inputs are active high, so that setting S to 1 will set the latch and setting R to 1 will reset the latch.

### What is an ambiguous condition in a NAND based S R latch?

Explanation: In a NAND based S-R latch, If S’=0 & R’=0 then both the outputs (i.e. Q & Q’) goes HIGH and this condition is called an ambiguous/forbidden state. This state is also known as an Invalid state as the system goes into an unexpected situation.

What is forbidden condition?

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).

What is the difference between the SR NOR with SR NAND )?

## Is NOR and NAND the same?

A NAND gate is equivalent to an inverted-input OR gate. An AND gate is equivalent to an inverted-input NOR gate. A NOR gate is equivalent to an inverted-input AND gate. An OR gate is equivalent to an inverted-input NAND gate.

## What is ambiguous condition in a NAND based SR latch?

What is an invalid state for the S-R latch?

Having both S and R equal to 0 is called an invalid or illegal state for the S-R Latch. Otherwise, making S=1 and R=0 “sets” the multivibrator so that Q LED is ON and !Q LED is OFF Conversely, making R HIGH and S LOW “resets” the latch in the opposite state.

What are the invalid inputs with SR latch with NAND gates?

“Now, lets consider, NAND gates, in SR Latch, the invalid inputs are S=0, R=0. But in enabled SR latch, the invalid inputs are S=1, R=1” Correct, because the gating inverts the S and R signals. “So, can I say, invalid inputs with SR Latch with NAND are: S=1, R=1” Correct “If enabled, then S=0, R=0” That is half-true.

### What is the forbidden state of a NAND latch?

\\\$\\begingroup\\\$For a NAND latch the forbidden state is when both inputs are low, not when they are both high. What you are calling the forbidden state is actually the “hold” state, where the latch holds its prior state as you observed. It would be easier to follow your schematic diagram if you used NAND gates rather than AND gates.\\\$\\endgroup\\\$

### What happens when s and R NAND latch inputs are equal to 1?

When S and R NAND latch inputs are both equal to 1, the outputs “latch” in their prior states. This is opposite for a NOR gate based SR Latch. Both input HIGH turns both LEDs OFF.