It has been a while since I last posted anything. Anyways, today I am going to write about the Little Man Computer (LMC). The LMC is a program that visually helps students understand how a computer works, it was created Dr. Stuart Madnick in 1965.

The little man has a calculator, a counter, In and Out baskets and a 100 mailboxes with zero based numbering. He opens each mail box, reads the OP-Code (operation Code) and executes that specific operation. This is what he can do:

• Load
• Store
• Add
• Subtract
• Input
• Output
• Branch on Zero
• Branch on Positive
• Branch Unconditionally
• Coffee Break / Halt

Combing these operations in a specified way create a program which runs the computer, essentially this is all what the computer does. The only true operations is add and subtract, the rest is either moving data around or branching to read other data.

The LMC model is useful for understanding the Von Neumann Architecture. There are three main guidelines that define this architecture. It includes the stored program concept, in which memory can hold both data and programs; in which the programs can be easily accessed and changed.  Also “memory is addressed linearly,”  in laymen terms memory locations are assigned a numeric address.  The third major guidline is the memory location has nothing to do with the data within that location.