Help with circuit design, dipsw not working in my desing

Does the simulation have a default value (high or low) for each and every input when starting up? This may be necessary so the simulator can set a state for every gate. It may be sufficient simply to attach high Ω pullup-or-pulldown resistors.
 

Hi,

simple answer:
* you clearly apply HIGH
* but you never apply LOW

A floating signal is "undefined". It may be HIGH, it may be LOW, it may oscillate, it may pick up noise / signals from nearby, it may change state at any time...

--> use pulldown resistors as Brad already mentioned.

Btw:
* almost every beginner made this mistake. Thus on a search you may find millions of the same informations that Brad and I just gave. Just do a search.
* if you have a simulation tool ... then use it. You used a LED to check the output state of a gate ... but the same way you could use a LED to check the input state of a gate


Don´t use external file servers. Just press the [insert image] button to add a picture.

Klaus
 

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