Multisim and Ultiboard

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Comparator not working correctly!

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Hi

I'm having an issue trying to get a simple 4585 comparator to work correctly (file attached) on the 'A0 - A3' inputs i have a 'clock' pulse (manually triggered using switch 'A', LEDs indicate binary), and on the 'B0-B3' inputs i have a hardwired '0101'. Starting from 0000, the output correctly shows OALTB (output A less then B). The problem is when it gets to 0101; not only does the expected OAEQB (output A equal B) NOT come on, but the OALTB doesnt go off, and the OAGTB comes on simultaneously!

 

Once the count goes above 0101, the OAGTB comes on as expected, and the circuit behaves.

Can anyone suggest anything?

 

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Solution
Accepted by topic author JohnSym

Sigh. I had the AGTB, AEQB & ALTB inputs set wrong. Got it now. Can i kudos myself? 🙂

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