[sdiy] How to add MIDI IN to an old Casiotone 101

Robin Whittle rw at firstpr.com.au
Mon Dec 30 02:39:16 CET 2013

If you can find an already made active low matrix kit which works with
the particular scanning system of these chips, that would probably be
the easiest approach.

Alternatively, if you are handy with a microcontroller and can write
your own, or copy, a MIDI parser, you can drive the switch scanning
system via dual-port memory chips.

In the early 1980s I used four 74LS170s.  I had some troubles at first
but this was due to a bad batch of chips.  Page 7 of the PDF:


has the schematic for using these chips so notes played on one Casio's
keyboard are played on a second Casio.  These are all of the early set
of Casiotone instruments with a single chip (or two for the CT-201 and
CT-202) which scans the keys and produces 14 bit digital audio output at
567.086kHz: the uPd771, 772, 773 and 775.

The 74LS170s could be difficult to get.  Unfortunately, as far as I
know, there are no 74HC170s.

 - Robin

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