Supra PiModem Project - Getting Retro PCs Online

Supra FaxModem 28.8 – this is providing the basis for the build and will also be the source for many of the components that will be used in this project

Banana Pi M2 Zero – This small SBC will provide the brains, not only to enable serial communication but also to control other aspects of the project

Pimoroni LED Dot Matrix Breakout – This will allow the project to emulate the dot matrix display found on the Supra FaxModem 28.8

TTL to RS232 Module – This little board will convert the RS232 signals into something the software can understand and is a rather common device for projects using SBCs

Lots of wiring, Custom perf boards, A Raspberry Pi Zero Hat from AdaFruit, LEDs and some rather intensive 3D Modeling to create the 3D Printed parts needed to put everything together.

Items used in this project
WiFi Antenna https://amzn.to/3AhOo2R
Dupont Connector Kit https://amzn.to/3KUBU6m
M2.5 Button Head Hex Socket Cap Screw Kit https://amzn.to/3AhEeiM
M2 M3 M4 Hex Button Head Socket Cap Kit https://amzn.to/3V15oEk
14 Pin DIP Sockets https://amzn.to/3mSxc0U
20x20x7 5v Fan https://amzn.to/3ouvqUj
Breadboard Jumper Wires https://amzn.to/3Ai3plu
TTL to RS232 Module https://amzn.to/3KUCi4O

Adafruit Perma Proto Bonnet https://www.adafruit.com/product/3203
Pimoroni LED Dot Matrix Breakout https://shop.pimoroni.com/en-us/products/led-dot-matrix-breakout

I would urge you to check out the accompanying YouTube video for this project.  It will have some visual details that I may be skipped in this modding article.

With that being said, let’s get started.

The Genesis of this project was a result of wanting more from my Retro PC experience.  Knowing that an internal modem would be worthless I started looking at external solutions.  I wanted a modem with a plethora of status lights and while a classic Hayes modem would have been perfect it would seem the owners of those devices are extremely proud and price the devices accordingly. 

That is when I started to expand my search and found the Supra line of FaxModems.  The Supra FaxModem 288 shown here is one of the more advanced designs that still used the extruded aluminum shell.

You will find four active LED lights on the front panel.  TR indicates “Terminal Ready” when the modem is has been booted up and issued the “OK” command.  OH indicates when the modem “Off Hook” and actively doing something while SD and RD indicate when data is being sent or received over the serial connection.

The real reason for choosing this modem is the dual 5x7 dot matrix displays.  On the factory modem these will output the Hayes modem responses and status messages.  For instance, when the modem is ready to be used it will display “OK”, when it is dialing it will display “Di”, once it has connected it will display the connection speed and current connection settings. 

For the most part, the display is really cool but, also a little redundant making it perfect for how I planned this project.