I teach a university class about the history of computing. To explain how early computers worked, I created the Toy CPU emulator - a reduced instruction set computer in the style of the Altair 8800 or IMSAI 8080. In this presentation, I'll explain how I created the Toy, and how to create and enter programs into the Toy. You enter programs into the Toy using "switches and lights" - the Toy simulates LEDs for each counter and instruction, and the accumulator value. We'll create a few simple programs and enter them into the Toy using 8-bit machine language. The Toy CPU is a great way to learn about machine language programming!