56%(9)5 out of 9 people found this document helpful
This preview shows page 1 - 2 out of 5 pages.
CPSC 121: Models of ComputationLab #4: Time-Division MultiplexingObjectivesIn this lab, you will be introduced to the method of time-division multiplexing which uses a type of circuit called ademultiplexer. You will also learn about the Arithmetic Logic Unit and see how multiplexers are used within it.1Pre-labImagine you are calling a friend in Asia. While you are talking, there is one signal connecting you and your friend.However, it would be too expensive to directly wire every telephone in North America to every telephone in Asia. Layingone wired connection across the Pacific Ocean is expensive enough.Have a look at the animation atmultiplexersystem.gif. Here we see asolution for wiring telephones in North America to telephones in Asia: have one wire between the continents, and connecttelephones from the two continents to either end of this one wire, as needed for conversations. (This technique is knownastime-division multiplexing.)TODO (pre-lab): In the animation, five conversations are being connected. Draw what it would looklike if six conversations were being connected.The connection scheme in the animation uses a circuit called ademultiplexerto undo the effect of the multiplexer. Themultiplexer selects the caller’s signal and passes it to the demultiplexer, which then selects the appropriate receiver tosend the signal to, thus connecting the two friends.A 1-to-2 demultiplexer has two inputs:s, analogous tos(select) in our multiplexer, andy, an input wire.It produces two outputs:x0andx1, the demultiplexed signals. It works like this:•Whens= 0,x0outputs the value ofy, andx1outputs LOW.