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This is referencing the article about state machines on allaboutcircuits.com In their state table, they have a 'Don't Care' listed under the output for the state 11. State Table However, in their k-map of the output column, they listed a '0' under 11, instead of a don't care. Why is that?

k-map

The article in reference: https://www.allaboutcircuits.com/textbook/digital/chpt-11/finite-state-machines/

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    \$\begingroup\$ Why do you care? \$\endgroup\$ – PlasmaHH May 1 '18 at 21:26
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    \$\begingroup\$ That's strange. I would rather use \$1\$, so \$Y=B\$. \$\endgroup\$ – Eugene Sh. May 1 '18 at 21:31
  • \$\begingroup\$ Why not use a 'Don't care' in the k-map? Instead of a 1 or a 0 \$\endgroup\$ – Yezen Armout May 1 '18 at 21:57
  • \$\begingroup\$ Because it is likely a mistake. \$\endgroup\$ – Eugene Sh. May 1 '18 at 22:03
  • \$\begingroup\$ the state diagram indicates that state 11 is undefined ... the state table has an error in Y ... it should not have a don't care since it is an output that is not used as feedback ... or the final k-map should have a don't care .... i think that it is a case of the designer adjusting the final k-map to give a desired output in case an undefined state is entered \$\endgroup\$ – jsotola May 1 '18 at 22:06
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Truth tables can be used to describe either what a circuit does or what a circuit needs to do. When a truth table is being used for the former purpose, any particular combination of stimuli would yield output values of high, low, or perhaps "unknown", but an output of "don't care" wouldn't make much sense. On the other hand, when a truth table is being used for the latter purpose, an output value of "don't care" may be used to invite indicate that a circuit will meet requirements equally well whether the output is high or low in a particular case.

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You're right, it's a mistake. The don't care Y could be rather taken as "1" and the K-map would minimize to Y = B.

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