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