LMC Input and Output

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The following program will demonstrate the INPUT and OUTPUT instructions of the LMC.
Running the program: the program simply INPUTS a number, then OUTPUTS it.



  • Copy the three-line program above and paste it into the Program box.
  • Click on the “Assemble Program” button.
  • LMC Input and Output Image 1After the program is assembled you should see RAM addresses 0 to 2 contain the machine code instructions shown in the image.
  • Click on the RUN button.
  • When prompted, INPUT a number.
  • If you have difficulty following what is happening, read the explanation below and use STEP instead of RUN so you can follow each step.


INP //the input value is copied into the accumulator.
OUT //the value in the accumulator is sent to the OUTPUT.
HLT //the program halts.

Example results