Harry Porter's Relay Computer:
A Video Tutorial

Posted: 15 November 2007

The Video

Here is a 60-minute video describing the design of the computer. The video includes the discussion of a number of circuits, the overall architecture, the instruction set, and concludes with an executable program.

Most of the video is a narrated PowerPoint presentation, but it also includes footage of the machine in action.

The full video is available in QuickTime format (i.e., MPEG-4 AVC / H.264 / .mov) in these pixel resolutions:

640x480 Approx 356 Mbytes; best quality.
320x240 Approx 78 Mbytes; reduced quality.

Supporting Material

Here are the PowerPoint slides used in the video. Click here for PDF or here for other formats.

Click here for the complete script.


Here is an 18-second sample of the video, so you can preview the image quality:

640x480 Approx 1.9 Mbytes; best quality.
320x240 Approx 456 Kbytes; reduced quality.

Outline of the Video

What is a Relay?
Schematic Diagrams
The NOT Circuit
The OR Circuit
The 1-Bit Logic Circuit
The Addition Circuit
The Zero-Detect Circuit
The Enable and Shift Circuits
The 3-to-8 Decoder
Overall Architecture
The Memory Unit
An Example: The ADD Instruction
The Clock Circuit
The Finite State Control
Timing Diagrams
Instruction Decoding
The Instruction Set
An Example Program
Concluding Remarks

About the Author

Harry H. Porter III, Ph.D.
Computer Science Department
Portland State University

Relay Computer, main page: www.cs.pdx.edu/~harry/Relay
Harry's Website: www.cs.pdx.edu/~harry
Short Bio: click here
Email: harry@cs.pdx.edu