How the Yamaha FM synth cassette interface works

Interesting article with some very useful information. This reminds me of a perennial, and mostly untouched back-burner project of mine :)<p>I&#x27;ve owned a Roland MC-202 Microcomposer for many years. It&#x27;s an early &#x27;80s analogue monosynth with a two track sequencer that&#x27;s a LOT of fun, but is infamously awkward to program. It allows you to dump sequences in an audio-based format to tape and load them back.<p>Rather than endure the slog of programming sequences directly on the machine, I&#x27;ve often dreamed of a workflow where you could program sequences in a UI, and then encode that information to generate an audio file that you could then load into the MC-202.<p>For example, it&#x27;d be relatively straightforward to create a web-based UI using HTML5 audio to create a simple sequence builder that you could then dump to some text&#x2F;cell format.<p>The challenging part would be using this information to encode the final audio file. I&#x27;ve done a little research, and I read the MC-202 uses an encoding format that&#x27;s similar to, but not the same as, the Kansas City Standard. One day I&#x27;ll dive into this (hopefully it won&#x27;t be too complex for me!)

Author here: Thank you so much for posting the article, I really appreciate it! The article actually began as a technical deep-dive into the internals of the Yamaha TX81Z. It seems as though most of the technology in the TX81Z is pretty well understood at this point. However I&#x27;d never seen anyone ever talk about how the cassette interfaces on the Yamaha synths actually worked. Figuring this out turned out to be way more fun than doing a deep-dive into the whole synth, and I got to learn a lot in the process. I know some people would definitely have already known how this worked. In my case, the synth is actually older than I am! I unfortunately missed out on the very interesting era of computing where this kind of technology was more common.

Data transmission over audio is still found in some more modern gear. The newer line of Teenage Engineering&#x27;s Pocket operator synths&#x2F;samplers, released in the late 2010s, also uses an audio-based format for import and export of its presets and patterns. You can find various presets on youtube. I don&#x27;t think anybody has reverse engineered it, though.<p>Similarly, the korg volca FM firmware update procedure happens by playing an audio file into one of the sync input jacks. This is odd considering it has a MIDI input port, which could load firmware via digital SYSEX commands, a fairly common method.<p>Another unconventional method I&#x27;ve seen recently is in the the Korg Gadget app. It implements song sharing via QR codes. The QR codes don&#x27;t point to an URL, instead they directly encode the song. Several of them are required, so it&#x27;s not super convenient, but it works ok. I&#x27;m not 100% sure why they have this option, but I think it might be the only way to do it in one of its platforms, the nintendo switch.

I bought a vintage Yamaha TX81z[1] a while back (you can still find them for ok prices on ebay) to play with some classic FM synthesis and sounds (note the tiny LCD front panel interface is painful to use, but you can use an external patch editor&#x2F;librarian); I believe it came with a cassette of the original presets (and possibly other data like a demo song or something.)<p>I haven&#x27;t actually tried to use it (I expect you can just download the sysex data from somewhere and send it over MIDI) but the Yamaha approach seems similar to cassette storage interfaces of old microcomputers from the 1980s (or earlier.)<p>Note a plugin like Dexed will give you 1980s-style FM (though DX7 6-operator&#x2F;sine rather than TX81z 4-operator&#x2F;various waveforms) for free, but the TX81z is a nice hardware synth that is also 8-voice multitimbral (!)<p>[1] <a href="https:&#x2F;&#x2F;www.synthmania.com&#x2F;tx81z.htm" rel="nofollow">https:&#x2F;&#x2F;www.synthmania.com&#x2F;tx81z.htm</a>

I know it doesn&#x27;t make sense but does anyone know where I can listen to some CUTS format audio? I&#x27;m just intensely curious about what it sounds like.

It’s aged great, you can simply use a personal computer instead of a cassette tape. Or even a digital recorder. Or <i>gasp</i> a cassette recorder!