For some reason my SN7425N the strobe input to U2A is ignored when all the inputs are 0. I checked the logic diagram for 7425 i still dont get it why it ignored the strobe input. Any suggestions will be very helpful. Thank you.

 

That's the expected behavior:

 

How to say expected behavior? I count my u1A output suppose to be high or did i count it wrongly. Ok, my u1a input for ABCDG = 00000..u2a ABCDG = 00001....by the way the irrelevant 'x' mean what? Thank you

 

Hello,

The irrelevant 'x' means that it does not matter wether the value is H or L.

Here is more comple data of the chip:



Bertus

 

Hello,

The irrelevant 'x' means that it does not matter wether the value is H or L.

Here is more comple data of the chip:

View attachment 124277

Bertus

Thank you for telling me now i knw 'x' mean the dont care term....i look at the function table my u1a output should be H then go to the input of u2a then u2a output will also be H then why the input strobe of u2a is ignored? Sorry for asking too much....this logic gate kinda interesting make me want to know how it function