The PSR-12 uses a custom processor with the Yamaha YM3812 OPL2 FM synthesizer, the same chip on the PC "AdLib" card used to play MIDI music, to produce sound along with the DAC YM3014. Hence it somewhat sounds very similar to PCs of the era. The FM synthesizer synthesizes instrument sounds much like how MP3s compress, instead of using a wavetable which would produce more realistic sounds. Because of the OPL2, it does have 9 voices so it supports a limit of 9 buttons pressed at the same time; though if percussion backfill is enabled, this is reduced to 6.

Though it has a full sized keyboard, it does not have key velocity detection like many of the more expensive keyboards of the time like many Korgs.

I got this at the outlet of a Goodwill for $1. It barely worked - it behaved very erratically and produced unexpected sounds, including a sound that tricked me into thinking it was producing 60 cycle hum. By ruling out possibilities this unit was probably mistreated and left outside in a damp environment and the keys are completely dirtied from the environment. The 6 UM1 "D" batteries inside were completely shot, including one of them leaked and subsequently dried up, leaving a crystal mess. The leaky cell, incidentally, was a Ray-o-Vac Alkaline. I hosed off the insides, treated the battery leak with vinegar, and cleaned out the key switches. After the cleaning, the Yamaha works once more as it should! The remants of damage remain on the unit - it seems like someone threw a hot solder iron on it, causing (more or less) unrepairable melt damage to the plastic in multiple places, and it's missing the plastic cover on the power switch. I may have to jury rig a switch cover if I can't find a suitable replacement.

Unfortunately I don't know how to play the piano but always had an interest in it. I don't know how to play any musical instrument though can type. Perhaps I could learn to play the piano on this.

I had played with a Casio PT-1 in the past and it seems its demo song is "Unterlanders Heimweh"