sinclair@aero.ARPA (William S. Sinclair ) (08/15/85)
I took a peek at the schematics provided by the Atari ST developers' kit.
The MIDI interface is essentially a Motorola 6850 ACIA driven by a SHARP
900 opto-isolator. Output apperas to be standard open-collector logic.
Ther are actually TWO 6850's in the box. The second goes to an output port
directly. I don't know for what purpose.
As far as I/O addresses, the chip select comes from the "glue" chip, so it's
not obvious what they are. I couldn't find a refernce to the addresses in the
ducumentation either. Perhaps the developers package contains a more detailed
I/O memory map, but I haven't found it yet.
Bill Sinclair 213/647-1753