Little Man Computer: 2. Branching Code

Little Man Computer is a model of a computer that was created to help students of computer science learn about assembly language programming and the Von Neumann Architecture. In this computer science lesson, you will learn about operations in the Little Man Computer instruction set that allow you to write branching code. These include BRanch if zero or Positive (BRP), BRanch if Zero (BRZ) and BRAnch (BRA). BRP and BRZ are decision making operations; they test the value in the accumulator and alter the contents of the program counter depending on the outcome of the test, this in turn causes the flow of control to jump to another program instruction. BRA is used to perform an unconditional jump. You will also learn about the role of the CPU’s Memory Address Register (MAR) and the Memory Data Register (MDR) during the fetch decode execute cycle.
Online LMC simulator by 101computing. https://www.101computing.net
Chapters:
00:00 Introduction
00:30 Summary of the Little Man Computer Instruction Set
00:52 A program to test if a number is bigger than a particular value
01:08 The 101computing LMC simulator
05:33 The CPU registers
09:34 A program to find the largest of two numbers
11:23 Exercises
12:16 Solutions