OndraMELODIK

Music interface for the famous czechoslovak home computer TESLA Ondra SPO186

SMD version with Joystick interface, but without printer connector by Solaris104 here: Ondra JOY/MELODIK.

You can read the OndraMELODIK story in this article (Czech language)

OndraMELODIK music interface - introduced in 2022

Czechoslovak home computer Tesla Ondra SPO186 - introduced in 1985

Features

• Opensource hardware
• Based on SN76489 chip
• Compatible with OndraSD interface, OndraMELODIK is through out interface
• It can play 3 channels square wave, 1 channel noise simultaneously
• Minimum CPU usage - two byte transfer, in some cases even one byte transfer, this is essential for such a slow computer
• External interface - no changes on the computer
• Designed with 80´ technology - all parts was available in 1985
• DB25 Centronics printer port (formerly known as LPT from PC) in one case
• 3D printed case STL files included

Usage

1. Turn off your belowed Ondra
2. Plug OndraMELODIK to Ondra X1 connector
3. Optionally plug the OndraSD or whatever interface to the OndraMELODIK

As music interface

4. Switch the switch to the MELODIK position
5. Plug the 3.5mm audio jack of your favorite audio system
6. Turn on Ondra
7. If you hear some noise or tone, just push once the RESET button
8. Load the software meltest.bin from this repository and test the device and listen the music

Notice: If you perform just Ondra reset and some tone or noise is coming out, just push the RESET button once

As printer interface

4. Switch the switch to the PRINTER position
5. Be sure you dont have plugged in the audio jack or the audio system is turned off
6. Plug your printer using standard PC printer cable
7. Turn on Ondra
8. Print using Ondra's monitor, BASIC or TEDIT (if you forget to unplug the audio jack and strange noises are coming out, it is normal)

Preview

How it sounds

https://www.youtube.com/watch?v=u5RyUs0VGdg

How it prints

https://www.youtube.com/watch?v=VYsxnQOKPeM

Real photos

License

MIT license