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

[rsdio at sounds.wa.com]

The 74148 8-line to 3-line priority encoder chip in that P6Retro kit  
is even more handy for this task than the 8-input NAND that I was  
talking about. Not only can it trigger an interrupt input on your  
microcontroller (its EO line goes High and GS line goes low) when a  
column become active, but it will also decode the column number for  
you on the A[2:0] outputs. This makes for a very fast response to  
sync with the Casiotone matrix scan.

There's also a 74147 chip with 10 inputs that encodes to 4 bits, but  
doesn't support all 16 hex codes.

Brian Willoughby
Sound Consulting


On Dec 29, 2013, at 04:02, Roman Sowa wrote:
> there are at least a few circuits to do exactly that, from CHD  
> ELEKTROSERVIS or Kenton and many others.
>
> this one is purely-DIY, in contrary to many commercial, ready to  
> use kits:
> http://www.angelfire.com/geek/srlabs/p6retro2.html
>
> works wth 8x8 matrix, but you can customize it