Hi Charles !
WIth great pleasure ! I will update my skype profile then will be connected tomorrow !
About the non-blocking Bconout: you can only write one byte at a time in the data register of the ACIA, it will not queue them and you'd loose the previously written value. So you have to wait that the ACIA sends the byte, then raises an interrupt to say it's ready to send another one (there you'll pull another one from your IOREC/buffer).
The MIDI spec says the rate is 31250 bits per second, 1 start, 8 data, 1 stop, no parity. That has never changed and probably will never change (serial connection will be replaced with USB probably in the future). You can send data "as fast as connection allows", but be careful with System Exclusive message : many "old" synthesizers will not be able to swallow them fast enough, so you have either to add some configurable delay between bytes or between messages. For example, my TX-81Z and SY-77 require some delay between sysex messages.
20 years ago I wrote a small XDD for FreeMiNT 1.15.12. I am just getting back to Atari programming and just transfering the sources of 1.18.0 to my ST to see what changed and if I can revive it somehow
I would like to try to make a program to use the ST as a synthesizer, using the soundchip as generator. I made some tries using Omikron basic to generate a saw wave (using the envelop generator with period depending on the note you play). You can make nasty effects, the ST can turn into a wicked solo synth ! Also tried generating FM samples it kind of works but needs speeding up, I thought I could create a program to generate sound and send them by MIDI Sample Dump to a sampler (I have a E-MU ESI 2000). Would also like to create an open source FreeMiNT-friendly sequencer, even if basic.
Will be happy to help or share