In 1980 I purchased a Casio M10, the first battery operated, portable, polyphonic digital keyboard. In the next year or two I developed modfications for this, the MT-30 and the MT-40. I published them in an offset-printed booklet and sent them to 300 or more people around the world who wrote to me, with a small payment.
At some stage I will put up a PDF of this here.
For now, all I have is a text file which describes how to drive the upD931 chip, as found in the MT-65.
If you have anything to add to this, or any relevant pages to link to, please let me know. Please do not republish this file elsewhere. It is best that I maintain a single copy here, which saves various out-of-date versions lying around causing confusion.
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