A working simulation as an aid to understanding microprocessors. The Peeko-Computer simulates the operation of a simplified microcomputer in order to teach the fundamentals of machine-code programming. The Peeko-Computer has ten easily learned instructions, and the display gives a visual analogy of the operation of a real microcomputer. Programs can be entered, single stepped, every step, to aid comprehension, each instruction mnemonic is displayed as it is encountered. The Peeko-Computer comes complete with a 16-page instruction manual, which contains examples to teach: The concepts of instructions and data Loads and stores Jumps, with conditions Addition, and the carry flag Multi Byte arithmetic Iteration.