LMC Input and Output Instructions
The following program will demonstrate the input and output
instructions of the LMC. The first instruction will copy a
three-digit number from the In Box to the accumulator, and the second
instruction will copy the value of the accumulator to the Out Box.
What you should do
- Click on the "LMC Simulator Applet" link to start the LMC
- Clear the Message Box and all of the LMC mailboxes -- click
the "Clear Messages" button and the "Clear" button if necessary.
- Copy the three-line program above and paste it into the Message
- Click on the "Compile Program" button.
- Click on the "Run" button.
- When prompted, enter a three-digit number in the "In-Box", and
press the "Enter" button.
What you should see
- After the program is compiled, you should see 901 in mailbox 0
and 902 in mailbox 1. The Program Counter should start at 0
(click on "Reset" if necessary).
- When you click on "Run" or "Step", the Message Box will describe
the actions of each instruction.
- After the INP instruction, the Accumulator has a copy of the
value in the In Box.
- After the OUT instruction, the Out Box has a copy of the value in
- The final value of the Program Counter is 2. This mailbox
holds 0 - the machine code instruction that tells the LMC to stop
executing your program.