(de)mux4 question

Hi everyone-

I'm working up to an MPG/HAL question...I'm pretty close to figuring it out, but in order to properly form my question I'd appreciate a little clarification of the term 'mux' as it pertains to, say a mux4 component.

My understanding of multiplexing is basically: many signals--> fewer signal carriers (let's say wires)
Like for example: you have many simultaneous phone conversations, and only 1 wire to send them over. I know there are lots of clever ways to 'share' the wire, but for simplicity let's say you give every conversation some small increment of 'time on the wire' and you rotate doing so through all the conversations fast enough that nobody notices.

The operation of a mux4, however, seems to be the exact opposite: you have two inputs (signal carriers) which, depending on their values, produce one of four possible outputs. To me that sounds like "you have a wire with multiple encoded (multiplexed) conversations, and you'd like only one of them to appear as output". In other words, de-multiplexing.

Do I have this completely backwards?

tnx,
Pat

mux4 is a multiplexor, it has 4 data input pins: in0,in1,in2,in3 and directs them to one output pin "out" based on the state of the select pins sel0 and sel1

There is a fancier multiplexor: mux_generic that has selectable data types and a selectable size (up to 1024 inputs)

The beauty of the Mux 4 component is that if you use a binary selector switch, you specify 4 different states with just 2 inputs.
There is a very detailed worked example of setting up a Mesa 7i76e MPG I did up on my build thread after some asked to explain what I did better.
forum.linuxcnc.org/show-your-stuff/32029...utter-build?start=20

I have since extended this to handle a 6 axis MPG on a remote pendant. That ws fun!. By the time I got there, I knew my way around HAL pretty well!

pferrick wrote: My understanding of multiplexing is basically: many signals--> fewer signal carriers (let's say wires)
Like for example: you have many simultaneous phone conversations, and only 1 wire to send them over.

Consider each of the inputs to the mux4 to be a telephone subscriber and the output pin to be the shared phone line.
Only one gets to drive the wire at a time.