I'm just about ready to post what I have to GitHub. It now includes documentation of the Playcard data format, tools to convert Playcard binary images to MIDI files (channel 1 melody, channel 2 obbligato, channel 3 chords), convert audio of a card swipe to binary and the other way around, change values in the header of a card to modify its settings, make the checksum on a corrupted card valid for testing what a real keyboard does with a seemingly valid card which is nonetheless damaged, a random card maker which creates batches of musically nonsensical but perfectly valid Playcards, and tools to decompile a Playcard into a special, documented MIDI format and the other way around so you can actually make your own Playcards from scratch.
The last thing I really feel I need before going public with this is verification that these new cards work on actual hardware. They work on an emulated CX5M with a UPA-01 cartridge. However, now I need to find a way to get card swipe audio into a real keyboard.
When I first became interested in Playcards in 2011, I found that I could take one of those suction cup telephone pickup coils, plug it into the headphone output of my stereo amplifier, crank the volume to near max, put the coil up against where the tape head is on the keyboard, and play audio and it mostly worked. Then years later I got a new amplifier and this stopped working. I had a method going using a speaker switchbox and that same coil, but I don't have that set up now. I'm sure one of those audio cassette adaptors for car stereos that only have cassette players and no CD or line in would work wonders. The problem is that the tape head type thing which actually gets the signal to the car's tape player is too big to fit into the card slot, and just putting it on the outside of the slot doesn't get it close enough. What I need is a Playcard-shaped device which will actually fit in the card slot, but has an audio cable coming off of it. I know such a thing almost certainly doesn't exist though.
Any thoughts appreciated!
