Trouble with Multiplexers

Thread Starter


Joined Oct 3, 2005
I'm working on my DSD Homework here and I'm having a little trouble with the following problem:

Originally posted by Problem 4-18 Logic and Computer Design Fundamentals (Mano 3rd ED)
Construct a quad 9-to-1 line multiplexer with four single 8-to-1 line multiplexers and one quadruple 2-to-1 multiplexer. The multiplexers should be interconnected and inputs labeled so that the selection codes 0000 through 1000 can be directly applied to the multiplexer selection inputs without added logic.
I know how to for example make a 32-to-1 Multiplexer out of two 16-to-1 Multiplexers. That's easy enough, but then again that's a very clear statement. I'm having trouble understanding what is meant by "quad" 9-to-1 multiplexer or "quadruple" 2-to-1 multiplexers. Could I have just have easily said that a 32-to-1 mux could be made from a "dual" 16-to-1 mux?

The book is very vague on the description of adding terms like "dual" "quad" etc to the beginning of fact I can't figure out the meaning at all. My only bright ideas are that they're talking about IC Chips (a quad 2-to-1 package meaning there's four 2-to-1 mux's on the IC with a common select). Either that they could be telling me to construct "four" 9-to-1 multiplexers with one 8-to-1 line mux's and four 2-to-1 line mux's. I can do that I think.

Does anyone have any hints or explinations on where I should start? Could someone clarify what the question is asking for? I think I could solve it from there.

Thank you,


Joined Aug 8, 2005
It means for you to design four 9-1 muxes, using four 8-1's and four 2-1's.

Should be simple enough, the output of each 8-1 is muxed with the 9th line by the 2-1's, just pay attention to the adressing.