To really understand computer programming, we will implement the simulation of a simple 8 bit microcomputer in Java.

A classic microcomputer consists of three major components:

  • The Central Processing Unit or CPU
  • The Memory, most of which is Random Access Memory or RAM
  • The Input/Output Subsystem to interact with the world
graph LR; IO["I/O Subsystem"]---CPU; CPU---Memory;

The CPU is where every programm actually gets executed. Everything the programm does is performed here. The memory is where the program and also all the data it uses is stored. And finally, the I/O devices can be anything from a keyboard, mouse, and monitor to virtual reality gear.

We will model each of these as a Java class:

public class Cpu {
    // ...
}

public class Memory {
    // ...
}

public class IOSubsytem {
    // ...
}

Next, let’s think about what each class needs to do.