Category Archives: CoCo

Tandy/Radio Shack TRS-80 Color Computer (CoCo)

Microsoft Visual Studio Code (PC/Mac/Linux) for CoCo cross development.

Microsoft Visual Studio Code for Mac (left) with extension to color code BASIC code for easy loading into Xroar emulator (right).

As mentioned elsewhere, there are some CoCo-related extensions available for the Microsoft Visual Studio Code editor. I did not realize that MS released this editor for Mac and Linux as well as Windows.

Here is the free editor:

Once installed, you can download (from within the editor) extensions.

Here are two extensions by Tandy UK — one for COLOUR BASIC and the other for 6309/6809 assembly:

There is another 6809 assembly extension available:…

It colorizes files ending in .a or .asm. 

I don’t see many details about the Tandy UK ones, but I am indeed getting colorized BASIC keywords when I have a .bas file.

Modern monitors that work with the CoCo 3!?!

In the 1980s and 1990s, there were many computers made that used a 15Khz analog RGB signal. These included the CoCo 3, Commodore Amiga, Atari ST, etc. There were a number of monitors to choose from to use on the CoCo 3, with one of the most popular being the Magnovox (remember them?) 8CM515. It supported RGB-A but also had composite audio/video so you could get the old CoCo 1/2 artifact colors when needed.

I thought the days of 15Khz was long gone. We have had a few solutions for hooking up a monitor to the CoCo 3, including an FPGA project, Cloud-9’s VGA converter, and the Switch-a-roo cable with a SCART converter box.

But Alexandre Souza on Facebook let me know they use all kinds of LCD monitors in Brazil, and pointed me to this list of modern monitors that still support 15Khz analog RGB:

One of the highly recommended monitors on the list is on Amazon for $139. It might take just as a cable to make it work with the CoCo, or possibly a bit of signal inversion (just like the old days).

Anyone know more on this?

FOR SALE: Ken-Ton SCSI Interfaces and RS-232 Dual Comm Paks

I have three Ken-Ton auctions going now:

  1. Ken-Ton SCSI Interface with ROM socket, EEPROM of RGB-DOS and cable:
  2. Ken-Ton SCSI Interface (only):
  3. Ken-Ton RS-232 Dual Comm Pak (two RS-232 device):

I may also be selling my SuperIDE interface, though I am currently using it just as a realtime clock. I need to find another clock solution before I let that one go.

CoCoPilot DELUXE: CoCoWiFi + SirSound + DriveWire + CoCoPi + More


  • 2019-05-10: Added a link to CoCoWiFi article, and uppercased DELUXE.

TLDNR: See the video at the end.

In 2015, Sub-Etha Software rocked the retro world with the announcement of CoCoPilot. (And by “announced” I mean “posted a blog article about how to install DriveWire on a Raspberry Pi. And by “rocked” I mean “posted a block article about how to install DriveWire on a Raspberry Pi.)

SirSound and CoCoWiFi product flyer.

In 2017, Sub-Etha Software raised the bar again by announcing SirSound, the serial port multi-voice sound “card” for the CoCo. (And by “raised the bar” I mean “posted another blog article”.)

In early 2018, Sub-Etha Software released details on CoCoWiFi, and showed you how to build your own for under $10 instead of waiting for Sub-Etha Software to actually manufacture them. (And by “released details” I mean “posted yet another blog article”.)

PreciousPak concept artwork.

In late 2018, Sub-Etha Software shocked the CoCo Community with the proposal to end all proposals: PreciousPak. (And by “shocked” I mean “posted a block article about something I think would be really cool but don’t have the hardware skills necessary to make happen so I hope someone else will do the work for me, please and thank you”.)

And now, in 2019, Sub-Etha Software is proud to announce…


CoCoPilot DELUXE is the result of dozens of man-minutes of thought on the subject of “what should I do with all the Raspberry Pi stuff I have on my desk?”

Much like how PreciousPak solves all our problems when it came to CoCo cartridge add-ons, CoCoPilot DELUXE strives to solve all our problems when it comes to CoCo bitbanger serial port add-ons. (And by “solves all our problems” I mean “wouldn’t this be fun to play with?”)

With CoCoPilot DELUXE plugged in to your CoCo’s built-in Serial I/O port, you will have:

  • WiFi Modem – Use any existing CoCo terminal program, and be able to telnet, ftp, etc. to internet servers just as easily as you used to call in to dial-up BBSes in the 1980s.
  • SirSound – Use the simple BASIC “PLAY” command strings that you already know and love, except add a “#-2,” and change PLAY to PRINT, and then you can play multi-voice background music while your BASIC program does other things.
  • DriveWire Server – Use NitrOS-9, SDC-DOS or the special DriveWire version of HDB-DOS to access virtual floppies over the serial port. Under NitrOS-9, you also have access to other DriveWire features such as virtual printing, virtual MIDI, and virtual reality. Except maybe not that last one.
  • Print to PDF – Print from any CoCo program (including graphics programs such as CoCoMax, ColorMax, Max-10 and Max Headroom) and have the dot matrix output be rendered as a PDF file you can then print on a modem printer. It can even print the old green bars and fake tear-off strips with the holes in it, just like the olden days!
  • CoCoPi Emulation – This portable device can also be expanded with an option USB keyboard, USB mouse, and HDMI monitor to act as a virtual CoCo running various Color Computer emulation programs.
  • …and more!

In this list, there are a few “new” things we can’t currently do. Printing from CoCoMAX 3, Tandy Home Publisher or any other graphical print software is not currently possible (is it?). A new layer would be written to interpret common printer “driver” codes (Tandy, IBM, Epson, etc.) — including color — and render the incoming data to an image that represents all the dots the printer would have printed. (Heck, we could even emulate the old plotter printer thing.)

SirSound could work the same as the hardware SirSound (API compatibility), but could be expanded to do more voices, and use better sounds. The Pi has simple libraries that can product multi-voice music.

WiFi Modem would be similar to the CoCoWiFi (Zimodem) project, but the “AT” Hayes Smartmodem commands would be different since we’d just use one of the many “serial to network” programs/scripts readily available.

All we need is a bunch of software, an RS-232 interface for the Pi, and some switches to select which mode you want the CoCoPilot DELUXE to be in.


CoCoWiFi fork of ZiModem updated to current 3.5 build.


  • 2019-05-03: I’ve had a report of my build not allowing you to type. I have seen this before, and am investigating this. Anyone else having issues? Also, I missed something in my merge which may have affected over-the-air updates (AT&U). I am pushing out a new build. Also, added a screen shot showing 3.5. Also, note about no ESP32 build.
  • 2019-05-04: I started over with Bo’s unmodified source code, then did my changes to zimodem.ino and zcommand.ino. I am still seeing the issue where, via USB serial connection, I can’t type of my TTL-to-RS232 adapter is hooked up. Without it, it works fine. I need to do some testing via the CoCo with it’s bitbanger and RS-232 Pac ports to see what behavior I get. In the meantime, I appreciate your feedback.

Yesterday I updated my fork of Bo Zimmerman’s ZiModem. My custom fork is 100% his code, with only some configurations changed to make it default to standard RS-232 signals instead of inverted like the Commodore uses. (Basically, it’s what his “Guru modem” firmware defaults to, and the over-the-air update changed to point to builds on my service. Guru modem only builds for ESP32, so eventually I just need to figure out how to modify the project so it builds Guru modem for ESP8266, I think.)

NOTE: I only built for the NodeMCU-12E ESP8266 module and the generic ESP8266 (whatever that is) module. I did not have ESP32 libraries installed so there is no build for that currently.

If you want to pull the source code and build it directly through the Arduino IDE, you can find my fork here:

The binaries I built are located here:

I also wrote up some instructions for updating that firmware from a PC, Mac or Linux machine without having to build it with the Arduino IDE. (I had to use these steps myself, since I couldn’t remember how it worked.)

NOTE: If you have the ESP8266 wired up to a TTL-to-RS232 adapter, you may find that firmware updates will not work. On my device (using the full-signal TTL adapter and a NodeMCU ESP8266), I had to unplug the 3.3V power wire that goes from ESP8266 pin to the TTL-to-RS232 board. That was enough to make firmware updates work. I’m still not sure why having the TTL adapter hooked up affects loading firmware over USB, but apparently it does.

A final option is to use the ZiModem built-in over-the-air update capability, which we haven’t gotten to test yet since this is the first time I’ve updated firmware for the CoCoWiFi fork. That is done through the command:


That should grab the latest build on my server. I believe it reads a .txt file from my server to get the version number and builds the filename out of that, then downloads that filename. You can also specify the version manually. Currently, there is a 3.4 build and a 3.5 build available on my site.


Please let me know if this works for you. You should see the startup banner (1200 baud) show 3.5:

ZiModem (CoCoWiFi config) 3.5

Original instructions on this WiFi modem for $10 can be found here:

Good luck!

CoCoFEST! near Chicago on May 4-5, 2019

Although I am not certain I will make it (hopefully at least a day trip on Saturday), the 28th annual “Last” Chicago CoCoFEST! is coming up soon. Find details here:

I am hoping to find time to update my fork of ZiModem firmware for the CoCoWiFi project, and also dig out some more goodies to donate to the Glenside Color Computer Club for their fundraising auction. If nothing else, maybe I can get those items there with some others that will be passing through Des Moines on their way.

More to come… I hope.

Sub-Etha Software announces more 2018 Chicago CoCoFEST! plans


Sub-Etha Software announces more 2018 Chicago CoCoFEST! plans

Des Moines, Iowa – March 14, 2018 – Iowa-based Sub-Etha Software reveals more plans for the upcoming 2018 27th Annual “Last” Chicago CoCoFEST! to be held April 21 and 22, 2018 at the Heron Point Convention Center in Lombard, Illinois.

“The biggest news,” says Sub-Etha co-founder Allen Huffman, “is that we will have Jolt Cola to drink during the road trip to Lombard, and maybe enough extra to share during the event.”

Among the new offerings at this year’s event will be CoCoWiFi, an inexpensive internet modem device that allows connecting the CoCo up to a WiFi network for accessing remote internet sites using telnet and other protocols. Both fully assembled and do-it-yourself kits are expected to be available, with pricing to be announced at the show.

CoCoWiFi is pretty cool,” says Huffman. “It looks like an old-school Hayes Smartmodem and can be used on any model Color Computer with any terminal program. If the MC-10 has a terminal program, I bet it would work there too. The best part about it is if you don’t wanna buy it, you can spend about $10 and put one together yourself without any soldering. But we’ll be glad to sell you one for much more than that.”

Another new offering will be SirSound, the serial port multi-voice sound device. SirSound provides (1980s) arcade-quality background music and sound effects from BASIC. It uses built-in commands with no assembly language or special drivers needed.

“SirSound is one of the funnest things I have ever worked on this month,” adds Huffman. “You can play the Frogger theme song just by typing a PRINT command. I expect it could also play the Pac-Man theme, too, but we haven’t tested that, yet.”

SirSound is still under development, as well as SirSound S (6-voices in stereo), SirSound Plus (SirSound with the ability to play stereo digital files) and Sir Sound S Plus. There will also be an open-source SirSound Jr project made available. It will have the most of the same features as SirSound, but will be limited to just 1-voice tone music. Beep beep.

“We also will have a selection of new-old-stock Sub-Etha items in original packaging for those who like to collect useless 5 1/4: floppy disks with photocopied instructions stored in plastic baggies. Of course, master disk images of all this stuff has been uploaded to the Color Computer Archive and will be available for free, too.”

Be sure to drop by Sub-Etha Software’s table in the main exhibitor hall during the event.

About Sub-Etha Software

Sub-Etha Software was founded in Lufkin, Texas in 1990, as a partnership between Allen C. Huffman and Terry S. Todd. It made it’s first CoCoFest appearance at the First Annual Atlanta CoCoFest in 1990, and it’s first Chicago CoCoFest appearance at the First Annual “Last” Chicago CoCoFEST! in 1992. They may be contacted online at

About the Chicago CoCoFEST!

The 27th Annual “Last” Chicago CoCoFEST! is sponsored by the Glenside Color Computer Club of Illinois. They may be contacted online at

Allen Huffman
PO Box 7634,
Des Moines, Iowa
Ph: 515-999-0227


SirSound video demonstrations

One year ago, on March 9, 2017, Sub-Etha Software announced the Sir Sound CoCo Sound Card, today referred to as SirSound, without the space. Today we present to you the first public demonstration of the project.

SirSound demo 1- introduction

This 7-minute video walks through the basic concept of the device, and shows how easy it is to convert BASIC “PLAY” music to use the SirSound device.

SirSound demo 2 – polyphonic music

This 4-minute video shows how multi-voice music will be handled. It demonstrates 3-part harmony, and also a quick version of the Frogger arcade game theme music, all from BASIC.

More to come…