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

[Robin Whittle]

A list member kindly reminded me of something which I think I knew in
the past but had forgotten: the 74HC670 is a tristate output version of
the 4 x 4 register file (dual port memory, in some ways) open-collector
74LS170.  My circuit should work with these, provided diodes are added
to the output pins.

Digikey and Mouser but not element14 have the DIP version.


 - Robin