
The keyboard was pretty dusty but after cleaning it, you can see the black badge:

Here more photos about its internals and back info:



I did a little of research and I found that the keyboard is a common M122 Spanish variant and the badge could be from the MIDI IBM Music Feature Card:
The rarest thing about this is that, that midi sound card is very rare here in Argentina and also, the keyboard came in a loot from probably, a bank that used these keyboards with the corresponding terminals.
I really don't know more, all help will be appreciated!