Today I was reading the Casper Electronics website, browsing some of the circuit-bent projects, and ran across a page on the Casio SA series of keyboards:

What interested me was the following line:

There will be an Amplifier chip ( No AN8053 ) common across the SA series and a mask programmed CPU which will be made by OKI and have the part No M6387-xx where xx is the variant for the specific keyboard it is installed in, in the case of the SA-5 it is M6387-16

Could this mean that there's something on those crappy little keyboards that can be decapped, dumped, and subsequently emulated?