1. DAT2343
LMC Simulator Usage
© Alan T. Pinck / Algonquin College; 2003

2. Accessing the LMC software
Map a network drive to:
\\woodroffe-13\courseware\dat2343\sonoflmc
the binary (executable program) form is in the directory: pgm
with the name: SONOFLMC.EXE
copy or run it from here

3. The LMC Window

4. The File Drop-Down Menu
Load
re-load previously saved mailbox contents from file
Save
save current contents of mailboxes to a file for future loading during a later LMC simulation session
Exit
same effect as the Quit button

5. Scrolling the Displayed Mailboxes
Only 10 mailboxes are visible at a time.
Use the scroll bar below the 10 mailbox text boxes to see other sets of 10

6. Entering Mailbox Values
Click in the mailbox whose contents you wish to change
Highlight and replace the old contents with a new 3 decimal digit value; or type a new 3 digit decimal value in front of the old value
Tab or click on another textbox to cause the contents of the one you just edited to be changed

7. The “Single Step” Button
Performs one cycle of the instruction cycle
loads “Last Instruction Done” with 3 digit value from mailbox with “Address” equal to the “Counter” value
increments the “Counter”
performs the operation indicated by the numeric instruction in “Last Instruction Done”

8. The “Go” Button
Performs the instruction cycle repeatedly until a Halt (numeric code 700) instruction has been executed
May be possible to interrupt this processing by clicking the “Halt” button

9. The “Next IO” Button
Performs the instruction cycle repeatedly until the next INPUT (code 500) or OUTPUT (code 600) has been executed
Note that the instruction cycle execution is halted after the IO operation has been done

10. Warning On Input Control
The INPUT (code 500) instruction does not wait for the user to enter a new value in the “Input Box”
The value in the “Input Box” must be pre-set before the INPUT instruction is executed.
Usual method: Enter first input value before starting execution; then run to “Next IO” and (assuming the IO was an Input) enter the next input value, before continuing.

11. The “Halt” Button
Used as an emergency attempt to stop a program’s execution when the program is acting under a “Run” or “Next IO” command, but is in a loop with no HALT instruction (or, for “Next IO”, no INPUT nor OUTPUT instructions) within the loop.

12. The “Reset Counter” Button
Resets the “Counter” back to 00
Does not cause the “Little Man” to start his instruction cycle

13. The “Quit” Button
Stops execution of the LMC simulator and closes the LMC simulator window

14. Demonstration of LMC Simulator Usage

15. End of Lecture