Ever wonder if you could output MIDI data to a MIDI synthesizer from your Diamond GOS equipped ATARI 8 bit through a MIDI MAX compatible interface? I didn't think so but I had to ask.  And the answer is:

YES - {video removed}

I came across a MIDI device handler(M:) and blogged about the adventure of writing a test program in ATARI BASIC. 

I have had the time to try it out with a Diamond GOS program written in machine code using the MAC65 assembler.  It seems that the handler, if loaded as an AUTORUN.SYS, will stay operational when quitting to BASIC or when running an APP.

The program DMIDITST.APP loads and then sets up the menu bar with a quit command. Then it places 8 icons for the C scale.  These where borrowed from a previous program. The M: device is opened for output to the MIDI interface. There is no error checking for the M: device and am not sure what will happen if it's not loaded.

I did note that after running SDUMP.ACC, the program stopped working.  This was most likely caused by the ACC opening the same IO channel for the printer that was opened for the M: device. Haven't run into an other glitches.

On the chance you have an A8, Diamond GOS, MIDI interface and a MIDI sound module, the disk with the m: device,  application, source and macro library files is attached.

Diamond MIDI test.atr

Create a Diamond boot disk with DOS and configuration files. Copy the AUTORUN.SYS and DMIDITST.APP to your boot disk.  Hook up your synth,  push in your Diamond cart, boot up the system, and load the app.

I used DOS 2.5 on an xe with st mouse, Diamond GOS 3 and MIDIMAX. There shouldn't be any reason why the program sill not run under Diamond 2.0. It would be nice to hear that someone else was able to get it to run on their system.