Your machine should offer the voter a choice of two candidates and record the votes using two $5-$bit binary counters. Polling is to be private but supervised by a human operator. The machine should be designed to run like this: $1)$ The supervisor pushes a button $($call it $$READY$)$ to enable the machine to record the next vote. $2)$ The voter chooses a candidate by pushing one of two buttons $($candidate A$$ or $$candidate B$).$ An LED associated with each button indicates the selection. The voter can change the selection any number of times. The vote will not be recorded until the next step. $3)$ The voter pushes a third button $($CAST$)$ to cast the vote. The machine should not accept any changes after this, nor allow multiple votes by the same voter. The voter then leaves. $4)$ The supervisor again pushes the READY button, enabling the machine for the next voter. Pushing the button also should clear the LED indicators so that the next voter does not see the choice just recorded. To summarize, your machine should have four logic inputs $($READY$,$ CAST, candidate$-$A$,$ candidate$-$B$),$ two LEDs to indicate which of the two candidates has been selected, and two binary counters producing the output, which is the count for each candidate. A video which shows the machine in action is posted in the same folder as this document. Of course, the digital logic circuits are hidden! The whole machine can be built using two dozen or so combinatorial logic gates $($AND$,$ OR$,$ NAND, NOR, NOT, and so on$)$ and sequential logic $($SR latches, D$-$flip flops, T$-$flip flops$).$ You won$$t need all of these things. Simulation Software We use Logic.ly for digital logic simulation because it's very easy to learn, works the same in Windows and OSX, doesn$$t throw adds or do other nasty things behind your back, and frankly is a lot of fun. But Logicly costs $$60,$ so use the free trial. It's the same software, just limited to $30$ days. You should have no trouble finishing well within the trial period. If not, consider it a life lesson: manage your time or pay the price!