Virtual Digital Projects

Calculator Construction Project

Welcome to the web site dedicated to recreational and educational "virtual" construction projects. Using a free program called Multi Media Logic by George Mills, which can be found at www.softronix.com, these tutorials will provide hours of fun and intellectual stimulation. By following the detailed instructions found here, you can "wire" and run many interesting and challenging designs of varying complexity.

1. Cylon Eye *
2. Lane Judge *
3. Traffic Light Simulation *
4. Morse Code Receiver
5. Tic-Tac-Toe Game
6. Simon Game
7. Elevator Simulation
8. Four Function Calculator Circuit
9. Central Processor Unit

Cylon Eye *

Remember the TV show Battle Star Galactica? The Bad Guys were robots that had an "eye" that went back and forth. This project presents two versions of the eye. A simple introduction to Multi Media Logic and the schematic capture facility.

Lane Judge *

This screen shot is JavaScript enabled. Click on the Lane Sensor buttons to see. It works the same way the Multi Media Logic virtual project does.

Traffic Light Simulation *

This project demonstrates the logic needed to drive traffic lights. In addition to the basic normal operation, it also supports emergency modes. Timing can be varied to achieve the most efficeint traffic flow.

Morse Code Receiver

This is a new twist on the venerable Code Practice Oscillator circuit. It will receive International Morse Code and translate it into plain text. Illustrates the use of a lookup ROM to convert Morse to ASCII.

Tic-Tac-Toe Game

This circuit implements a heuristic developed by Tom Pittman of Tiny BASIC fame to play Tic Tac Toe. See if you can beat it. Demonstrates how a simple processor can be used to perform complex logic functions. The source code for the control ROM is provided.

Simon Game

This is a version of one of the first electronic games. The original was round with four large colored buttons. It would play a light and sound sequence that you were expected to repeat. Miss a code, and you lost. This project will test your short term memory.

Elevator Simulation

Imagine entering a three story building. You need to go to the third floor, so you decide to use the elevator. You press the car call button, the doors open, you press the third floor button, and up you go. This circuit implements the logic needed to control the door motor, lift motor, and status indicators for a virtual building elevator.

Four Function Calculator Circuit

Calculator showing result of dividing 22 by 7
This advanced project performs addition, subtraction, multiplication, and division on 8 digit signed floating point numbers. It implements a custom 4 bit processor with 2048 sixteen bit words of micro-code ROM. This project includes several "Design Puzzles" to challenge your logical design skills. It is broken down into subsystems, steps, and tasks to facilitate easy comprehension. Source code for micro-code ROM part is provided.

Central Processor Unit

A complete CPU circuit that includes keyboard input, ASCII display, programmable RAM, Arithmetic Logic Unit, etc. The programming model includes an Accumulator and four different addressing modes: Immediate, Implied, Absolute, and Indirect. An assembler written in JavaScript is included.

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