The Little Man Computer

A simple imaginary computer for teaching beginners how a computer works.

Most computers in used today have what we call the von Neumann architecture, name after the brilliant mathematician John von Neumann, who is credited with coming up with the concept, although the credit really belongs to German engineer Konrad Zuse who built the first computer the Z1, on these principles.

Computers where too expensive in the early days to have in home or class rooms, so Dr. Stuart Madnick came up with a simplified paper version of imaginary version of such a computer called the Little Man Computer.

I have actually written about this concept before: Learn Assembly Programming the Fun Way.

That was about various games to learn assembly programming. Several of these are based on the Little Man Computer (LMC) concept. But here will use two LMC simulators. We got two of these:

• 101 Computing Simulator. The most fancy looking of the two.
• Robo Writer Simulator. Plain and primitive looking, but this one lets you assemble programs with another tool and load up the generated machine code.

The image below shows the 101 Computing Simulator. On the left you see the assembly program to run. In the green boxes in the middle you got the inputs and the output to the computer. On the right you can see the contents of all the 100 memory cells of the LMC computer.