Nope!hi PG,
Is this a Homework problem.?
Mod.
When both or one of the inputs are floating; in other words, not being driving by any external value.What’s the point of the three rows with x in them? You have the complete truth table within the box.
Thanks for letting me know this!Hi PG,
Unconnected TTL Inputs assume a Logic High.
E
Updated:
Unconnected CMOS Inputs can assume either a Logic Hi or Lo
A logical truth table shows the expected output value for each combination of input values.Hi,
I take that an "x" stands for an unknown value which could be either "1" or "0". Is the table shown below for NAND correct? I'm focusing on the three rows with x's.
View attachment 267905
I'm sorry but I don't follow you. I've always thought that an "x" means either 0 or 1. I'm sure I've read the same at many places.An "X", as the input state, usually means that the input state doesn't effect the state of the output.
Thank you!hi PG,
The letter 'X' denotes the Result of the logical function, ie: the Output.
Look at this PDF.
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Added a link that may help.
https://en.wikipedia.org/wiki/Don't-care_term
https://en.wikipedia.org/wiki/Don't-care_term#X_value"Don't care" may also refer to an unknown value in a multi-valued logic system, in which case it may also be called an X value or don't know.[16] In the Verilog hardware description language such values are denoted by the letter "X". In the VHDL hardware description language such values are denoted (in the standard logic package) by the letter "X" (forced unknown) or the letter "W" (weak unknown).[17]
Hi PG,But doesn't it also say that an 'x' value could be an unknown.
"x" as an input means that that value is "Don't Care". The output does not change whether that "x" is 0 or 1.Hi,
I take that an "x" stands for an unknown value which could be either "1" or "0". Is the table shown below for NAND correct? I'm focusing on the three rows with x's.
View attachment 267905
Unknown, usually called "Don't Care" and unconnected are ***not*** the same thing. All inputs to logic gates must be terminated to a high or low state. They just must. We can go through another 18 posts, but the answer will not change.But doesn't it also say that an 'x' value could be an unknown.
Yes. but it is traditionally interpreted as a "don't care" state when resolving the output state.I'm sorry but I don't follow you. I've always thought that an "x" means either 0 or 1. I'm sure I've read the same at many places.