Need help in constuction of basic queuing system

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whompah

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Construct a basic queuing system that is used in banks, counters. Given a situation that Mr.A in room 1 and Mr.B in room 2, both of them have a push button which gives +1 logic when pushed and 0 when released. Here is the conditions needed to be fulfilled:
1) If. Mr. A pushes the button, 1 will be displayed in the LED 7-segment display
2) if Mr. B pushes the button, 2 will be displayed in the LED 7-segment display
3) If they press the buttons together at the same time, Mr.A takes priority and 1 will be displayed.

1 and 2 i definitely know, but i don't know how to implement condition 3 although it sounds very very simple. Hope seniors here can enlighten me. Thank you
 

hi and welcome,

If you post what you have done for #1 and #2, we could give you some ideas about #3.
 
View attachment 63213
attached screenshot is here, if condition 3 is to be taken into account, then i think the entire system has to be modified, but the attached screenshot is my basic idea.
Thanks for replying
 
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View attachment 63239
thanks for the help. but so far I constructed 2 different designs with same circuit parameters (Vcc=5V and all resistors value=250ohm) and i found out something. Check out the 2 attached pictures.
why is the leakage current different ?
and what is the effect of current flowing back to the output of IC logic gates ?
 
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