logic functions?

harvez_007

Joined May 2, 2008
2
Hi.

I am having heaps of trouble understanding how this works:

____________
______
___ __
X = A.B + A + C ?

How do i draw a logic circuit using this function?

What do all the lines mean and do?

Could you please explain it to me, that would be great

Cheers.

mik3

Joined Feb 4, 2008
4,843
A' means A with the line above because i cant write it. It means that the value of A is inverted, that if A=1 then A'=0 or if A=0 then A'=1

In the logic function it means that you put a NOT gate after the function that is inverted.
For example, if you want the logic circuit of (AB)' you will put an AND gate and then a NOT gate on the output of the AND gate.
If you have A', then you put a NOT gate on the output of A which is a signal from a device.

In your case, (AB)' means that you need an AND gate (for AB) and a NOT gate on its output (to implement the inversion noted by ') which is equivalent to a NAND gate. Then you will need a 3 input OR gate, on its inputs you will connect the output of the NAND gate, the A input signal and the C input signal. Finally, to implement the inversion denoted by X' you put a NOT gate on the output of the OR gate.