Extra midi ports on the Atari

[Tony Allgood]

Apologies if you have already seen this.... something odd is happening
to my mails.

Hi all,

I have just built BJ's extra ports for the atari off his web site. It
seems to work OK when being used with just one active midi channel.
However, the moment I play a whole song ie, at least four active
channels at any one time, I get hanging notes, involuntary pitch bends,
and general chaos. Is this normal or have I done something wrong? The
add on hangs off the RS232 port and consists of a multiplexor, 74HC138
with a few resistors and caps. It derives its power off the port itself.
I have yet to hook the scope on it yet, because to be honest, I am not
too sure what I should be loking for. I am using Cubase V3 with
export.drv installed.

Regards,

Tony Allgood, Cumbria, UK

Rack mounted moog filter and the TB3030 SuperBassline projects:

http://aupe.phys.andrews.edu/diy_archive/schematics/oakley/