I'm trying to design a 3 bit number comparer, but I'm not sure how to output what I want since it would be the larger number.

My algorithm is simple:

if (a2 > b2):
return (a2, a1, a0)
else if (b2 > a2)
return (b2, b1, b0)
else if (a1 > b1):
return (a2, a1, a0)
else if (b1 > a1)
return (b2, b1, b0)
else if (a0 > b0)
return (a2, a1, a0)
else:
return (b2, b1, b0)

What type of gate could I use that would allow me to return 3 bits?

Thanks

 

A normal multiplexer is a 1 bit mux which outputs only a single bit. You can use an n-bit mux to output n bits.

Buy I guess a 3 bit comparator requires only a few gates like AND and XNOR. In digital design morris mano book there is an example of 3-bit comparator using gates. Check it out

 

you wouldn't happen to have the page number would you?

 

163-165 2nd edition morris mano "digital design". Heading is "magnitude comparator"

 

If you care for a ready made solution, check here:
http://pdf1.alldatasheet.com/datasheet-pdf/view/8074/NSC/7485.html

This thread might be useful too:
http://forum.allaboutcircuits.com/showthread.php?t=42779

 

This sort of works, but I really need the actual vector of bits. Is it possible to do?

 

Oh, I get what you want. Use the output of the suggested circuit to drive a triple 2-to-1 MUX. That will select between your two outputs.

Is that clear?