I want to design a 2-bit ALU that does XOR, OR, AND, and addition. With help of Wikipedia:

I designed this:

enter image description here

However, it's not working. I tried connecting the controllers to S0, S1, S2 but no difference... Any help would be appreciated.

  • 2
    \$\begingroup\$ "It's not working" is very vague. Where did you build it? In a Simulator or on a bread board? What exactly, isn't working? \$\endgroup\$
    – Tyler
    Dec 13 '18 at 20:51
  • \$\begingroup\$ @Tyler In a Simulator(circuitmaker), you can see it in the photo! Nothing's working. when I change the value of inputs nothing changes, not in AND, OR, XOR and Addition \$\endgroup\$ Dec 13 '18 at 21:24
  • 1
    \$\begingroup\$ If "nothing's working" then the simulator is broken, or you haven't connected things properly, or you aren't using it correctly. How can we possibly diagnose your problem from a low-resolution graphic of your schematic? \$\endgroup\$ Dec 14 '18 at 1:34

Obviously, you need to connect your opcode switches (V1, V2, V3) to the select inputs (A, B and C on the top diagram, S0, S1 and S2 on yours) of the muxes. Also, you need to pull the enable (E pin) low on each of the muxes.


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