Thread Like Summary
=CO=Windler, Duke, pmackinlay, R. Belmont, Stiletto
Total Likes: 10
Original Post (Thread Starter)
by MooglyGuy
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?
Liked Replies
by Revenant

Volume envelopes are still kind of rough, but the rest is coming along. I'll probably clean it up a bit more after Thanksgiving.
4 members like this
by Revenant
Alright, problem solved! Time to start getting this driver to make some noise, I guess.

[Linked Image from]

I think the older models with the OKI CPUs might use the 8-bit version of the format from these patents, but I don't really have a way to verify that right now. Still haven't looked any more into how the CTK-2100 does audio yet either.
2 members like this
by Revenant
Just to bring things back to the original topic, here's a close-up of the off-the-shelf Holtek HT37B90 MCU from the SA-46 (first released 2010, still sold today).

Mine has an embossed datestamp of 2019-2020, so definitely not the original production run, but they probably all use the same MCU. As far as I can tell, the SA-65/66 (and SA-75?) from 2001 were the last to use the MSM6387.

[Linked Image from]
2 members like this
by Revenant
I mirrored a bunch of service manuals from various sources, mostly late-90s onward, organized by CPU:

The upd91x directory has the GT913 and related (uPD912/913/915). ML6763 looks like another ARM-based COB like the uPD800468.
1 member likes this
by Revenant
Originally Posted by R. Belmont
Nice of them to label all of the MCU's pins. I assume this is ARM based?

The architecture is Holtek's own 8-bit thing; the datasheet has more info. There are also a bunch more (unused) I/O pins that aren't exposed by that little breakout board. The ROM is still all internal, naturally.
1 member likes this
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