Thanks for the reply. Have an assignment to make a digital bowling
pin counter. Have the circuit working. Not sure how to express the
logic for the assignment. For example, a 3 can be pins 1,3,5 or
2,3,5. It really does not seem like this lends itself to a truth
table. I will keep looking. Most of the truth tables we covered were
conventional and simple.
Do you really want any 5 from 10 or do you want a more manageable any
3 from 5?
Any 5 from 10 can be fairly "simply" done using 252 five input AND
gates and one 252 input OR gate.
If you want exactly 5 from 10 then you need 252 ten input AND gates,
1260 NOT gates and one 252 input OR gate.
3 from 5 is more manageable in practice needing 10 three input AND
gates and one 10 input OR gate. Make that 10 five input AND gates, 20
NOT gates and one 10 input OR gate for exactly 3 from 5.
In general for M from N you'll need
X M input AND gates and one X input OR gate
or
X N input AND gates, X*(N-M) NOT gates and one X input OR gate
where
N!
X= --------
(N-M)!N!
Of course, you can express those AND gates as combinations of two
input AND gates and those OR gates as combinations of two input OR
gates and then optimize. (I'd recommend writing or finding a program
to do this!)
Tim.