Simple Music Synthesizer demo

intvnut · September 13, 2010

I put together a simple Music Synthesizer demo for the Intellivision ECS's Music Synthesizer keyboard. It currently just plays straight square waves, but it shouldn't be difficult for someone to make it more interesting. I wrote this because so far there hasn't been any software from outside Mattel that made use of the synth keyboard so far as I know.

I have also gotten a couple requests asking if I knew of any software that let you make a wider range of sounds on the Inty via the synth keyboard. I don't, and this demo doesn't do that, but it should be easy for someone to add code to this to do that.

One thing I discovered is that, unlike the ECS alphabetic keyboard, the synthesizer actually has all the required diodes to allow you to get an exact scan of what keys are pressed versus released. That has two implications: One is that I can't use a transposed scan like I do with the alphabetic keyboard, but that also means I don't need to; the other is that I need different scanning routines for the alphabetic keyboard vs. the synthesizer keyboard if I want to do a good job at both.

The attached zip file should have everything you need to build the synth demo, including an updated version of cart.mac and some of my other utility functions as well.

Usage:

Play up to 6 notes simultaneously on the synthesizer keyboard. The display will show you which keys it sees pressed, and which channel (1-6) the tone for that key got allocated to.
To transpose the keyboard, press 1/4 on either controller to shift up/down 1 octave, or 2/5 to shift by half-steps. You can reset the transpose to the default by pressing C or 0. The display will show the range of notes that the synthesizer keyboard currently maps to.
To change the volume, press 3/5 to increase/decrease the volume. E resets the volume to 10.

That's pretty much it. I threw this together pretty quickly (basically this afternoon over the course of a few hours), so I apologize if it's a bit rough.

Enjoy!

synth.zip

Edited September 13, 2010 by intvnut