MIDI-80 for the TRS-80

Description

MIDI/80 is a powerful and versatile General MIDI (GM) sound card for the TRS-80 Model 1, III, and 4. It is also a full-fledged MIDI interface.

GM sound is either produced by a Waveblaster-compatible sound module that plugs onto the MIDI/80 Waveblaster header or via a GM expander, such as the Roland Sound Canvas SC-55 or Roland MT-32, connected to MIDI/80's MIDI OUT DIN socket. MIDI data can be sent to either or both of these devices.

Standard MIDI IN & MIDI OUT DIN sockets (optional) turn your TRS-80 into a powerful MIDI processor. You can connect a standard MIDI keyboard to the MIDI IN DIN socket, and record MIDI messages with the TRS-80 into memory. MIDI messages can also be played back from the TRS-80 memory. The MIDI data recording is fast enough to allow for the real-time recording of entire multi-track complex GM songs.

Software for the TRS-80 is under active development. So far, we have a TRS-80 DRUM TRACKER, a TRS-80 MIDI SYNTHESIZER, and demo songs.

Details

MIDI/80 is a MIDI Sound & MIDI Interface card for the TRS-80 Model 1, III, and 4.

TRS-80 Model with Expansion Interface, MIDI/80, and Orchestra 85 replica:

TRS-80 Model III with MIDI/80 and FreHD HD emulator connected to the MIDI/80 expansion port pass-through edge connector:

MIDI/80 on a TRS-80 Model 4 with TRS-IO++:

Features

MIDI/80 offers:

A powerful and sonically impressive, versatile General MIDI (GM) sound & MIDI interface card for the TRS-80 Model 1, III, and 4.

GM sound is either produced by a Waveblaster-compatible soundmodule that plugs onto MIDI/80's Waveblaster header, or via a GM expander (such as the Roland Sound Canvas SC-55 or Roland MT-32) conntected to MIDI/80's MIDI OUT DIN socket. MIDI data can be sent to either or both of these devices. Both the Waveblaster module as well as the MIDI DIN sockets are optional, but in order to act as a soundcard, either of these options need to be present.
Standard MIDI IN & MIDI OUT DIN sockets (optional) turn your TRS-80 into a powerful MIDI processor. You can connect a standard MIDI keyboard to the MIDI IN DIN socket, and record MIDI messages with the TRS-80 into memory. MIDI messages can also be played back from the TRS-80 memory. The MIDI data recording is fast enough to allow for the real-time recording of entire multi-track complex GM songs, i.e., from a PC playing back a .MID MIDI file via MIDIBAR.
Stand-alone mode: equipped with a Waveblaster sound module, MIDI/80 is also a "headless" GM expander, not unlike the Roland Sound Canvas SC-55 (without display though). The MIDI/80 firmware provides a standalone MIDI mode - this mode is enabled by putting DIP Switch 3 into "ON" position. No TRS-80 is required in this standalone mode, only a 5 V power supply and an external amplifier.
Compatible with popular TRS-80 standard expansions: Model 1 Expansion Interface, FreHD, Orchestra soundcards, Talker/80, etc.
OpenSource BluePill firmware, Gerbers, and TRS-80 software available here.
TRS-80 software available, and more under development: Drum Pattern Tracker, MIDI Recorder, TRS-80 Synthesizer, etc.
DIY friendly: only thru-hole and off-the-shelf components are used.
Inexpensive: MIDI/80 can be assembled for ~35 USD. The most significant cost factor is the Waveblaster module, if required. If you already own an external MIDI expander such as the Roland Sound Canvas or similar, no Waveblaster plugin module is required.

Technical Details

Requires standard 5V "wall wart" power supply; 1 to 2 Amps, center positive.
Requires an external stereo amplifier to be connected to the standard 3.5 mm stereo audio jack.
Powerful BluePill STM32F103C8T6 Microcontroller clocked at 75 MHz (ARM Cortex-M3).
Compatible with all Waveblaster soundcards from Serdashop that don't require a 12 V supply.
Uses off-the-shelf Adafruit MIDI breakout module. The MIDI sockets are optional, as is the Waveblaster sound module.
Five activity LEDs that indicate read and write activity on the TRS-80 IO bus related to MIDI/80, as well as incoming and outgoing MIDI message activity. Useful for debugging MIDI problems.
Full TRS-80 expansion port pass-through. MIDI/80 is a "good citizen on the bus" and compatible with Talker/80, FreHD, Orchestra 85 and 90, etc.
Reset button on the BluePill microcontroller.

Demo Videos

You can get a better understanding of MIDI/80's capabilities and features by watching some of these YouTube demo videos:

Overview & Usage

Connect the...

Retro Computing Meets Electronic Music: The Downpoly TRS-80 Rig
Michael Wessel • 06/08/2026 at 14:53 • 0 comments

DOWNPOLY played a LIVE GIG at the Vintage Computer Festival Southwest (Dallas) 2026 https://www.vcfsw.org/ and gave YouTuber MONROE WORLD https://www.youtube.com/@darkuni an interview and tour of his TRS-80 rig:

"While out at the convention in Dallas/Fort Worth, I had the absolute pleasure of catching up with Joel, better known as Downpoly. What he has going on is absolutely crazy—he is bridging the gap between retro computing and modern electronic music using vintage TRS-80 microcomputers.

Joel walks us through his incredible setup, utilizing Michael Wessel's MIDI-80 interface and George Phillips' Orchestra 90 organ software to push these classic machines to their absolute limits. We dive into the production of his albums, how he uses a Tandy 2000 running Windows 1.0 to generate his album artwork, and his complex pedal and synthesizer chain.

As a massive advocate for physical media, I was especially thrilled to see his custom colored vinyl pressings and CD releases for his albums. It is an amazing mixture of digital and physical art that lines up perfectly with what we do here on the channel.

Be sure to check out his music and support his physical media releases using the links below!

Support Downpoly:
Website & Merch: https://downpoly.com

Listen At:
https://open.spotify.com/artist/7oj8N..."

I absolutely LOVE the MIDI/80 + TRACKER rig Joel has created:
DOWNPOLY's new album released!
Michael Wessel • 03/07/2026 at 19:29 • 0 comments

Joel Hilliard aka DOWNPOLY released his new album, TETHER_:

Unlike his previous album where MIDI/80 and TRACKER were mainly used for drums (it couldn't do more back then!), he is now increasingly utilizing it for full backing tracks on his songs (for bass, melodies, chords, ...). By now, TRACKER is a full-fledged 6channel multi-timbral MIDI sequencer (organized into 26 pages which can be flexibly sequenced in song mode). More MIDI channels can be realized by synchronizing multiple TRACKERs running on dedicated TRS-80s via the parallel port sync cable (see below). Joel is tpyically using 2 to 3 synchronized TRACKERs for his work. See below for more details.

Please support his work on Spotify if you like his songs on YouTube (also see here.)
X-MEM/80 Enables Playback of Very Large MIDI Files with MIDI/80
Michael Wessel • 11/09/2025 at 06:37 • 0 comments
With X-MEM/80 we can finally play back large MIDI files!
Michael Wessel • 09/07/2025 at 18:31 • 0 comments

I have created a new 512 KB bank-switched memory expansion for the Model I - with it, and a slightly updated MIDI player program that can make use of the extra memory, I am finally able to play back large MIDI files. Demo video:
Thanks for the Blog Entry, Hackaday!
Michael Wessel • 06/02/2025 at 21:41 • 0 comments

Really appreciate it, Hackday - thanks much!

https://hackaday.com/2025/06/01/its-midi-for-the-trs-80/
Tracker tutorial video online!
Michael Wessel • 04/24/2025 at 04:00 • 0 comments

I have uploaded a short Tracker tutorial (Version 1.98 at the time of this writing) to YouTube; a recent customer asked for some form of documentation, as I currently don't have anything about the Tracker program in the Github repo. Here you go, hope it helps!
DOWNPOLY uses multiple synchronized Trackers!
Michael Wessel • 04/12/2025 at 01:40 • 0 comments

Here is the latest creation from DOWNPOLY, who is by now using MIDI/80 Tracker 1.98 and its parallel-port clock synchronization mechanism in order to synchronize multiple MIDI/80 Tracker machines:
Synchronizing multiple Trackers via parallel port clock
Michael Wessel • 03/29/2025 at 18:02 • 0 comments

It is now possible to synchronize multiple Trackers running on different machines:

Here is a demo video.

The latest version of the Tracker, Version 1.96 (tracker5/cmd on the disk images) is now sending an external clock signal over the parallel port, on Data 0. Another TRS-80 Tracker can then be configured to latch on to this external clock by setting it into external clock mode with the ' key. The receiving TRS-80 Tracker is called the secondary, and the clock generating Tracker the primary. Enable the external clock mode on the secondary with the ' key. Then start playback as usual, in pattern (P) or song playback mode (!). As usual, you can always refer to the help page for key bindings (H). The secondary Tracker is frozen until it starts receiving the clock signal from the primary Tracker via the parallel port cable; the tempo setting of the secondary will be disregarded, as the tempo is determined by the external clock from the primary. External clock can be en- and disabled using the ' at any time; also, with the exception of the tempo setting, recording and all the other Tracker operations and settings work identical as if the internal clock was used.

To make the cable, simply connect the Centronic ports of the two machines as follows: GND to GND (e.g., Centronics pin 2; note that there are multiple options for GND), and the Data 0 output (Centronics pin 3) of the primary to the BUSY input (Centronics pin 21) of the secondary. And easy way to construct the cable is to cut two TRS-80 printer cables in half, and solder the wires together:
Tracker Updates & Behringer Wave!
Michael Wessel • 03/22/2025 at 17:49 • 0 comments

... celebrating the newest member of the TRS-80 MIDI Studio: the Behringer Wave, a clone / recreation of the legendary iconic PPG Wave 2.3 from 1982! Created by Wolfgang Palm, the inventor of Wave Table Synthesis, in my birth-town Hamburg, Germany.
It's mind boggling how much he achieved with so little, back in the day. All of the PPG software was programmed in bare-metal 6809 assembly language, no C-compiler, no libraries, nothing.
Thank you, Behringer, for bringing this legend back to life, and for making it affordable! Now everybody can experience the magic that radiates from the legendary instrument. The build quality and sound is amazing!

Just getting my feet wet, but here is first demo using the latest MIDI/80 Tracker 1.95 and the S2 for drums. Enjoy!
Small Tracker 1.91 Demo!
Michael Wessel • 03/17/2025 at 14:17 • 0 comments
Finally, the Tracker software is becoming more feature complete. By now, I have
- multiple patterns (A-Z)
- pattern chaining = song mode (a song is a sequence of patterns, and can be looped)
- load & save
- MIDI real time tracking via MIDI IN socket from a MIDI keyboard
- real time tracking from the TRS-80 keyboard
- quantization
- some pattern tools (e.g., the ability to copy patterns)
- etc.