On Sunday 04 July 2010, Gordon JC Pearce wrote:
On Sun, 2010-07-04 at 22:16 +0100, Dan Mills wrote:
You could probably hack a multi serial port card
to do multiple midi
ports (Change the rock to give a suitable divider for 31250 baud
(4MHz?), add current loop interfaces)...
Been there, done that - when I was a penniless dole-scrounging scruffy
university drop-out living on a farm in the middle of nowhere, I decided
I needed a MIDI sequencer. So, I modified an old serial card with a
4MHz crystal which divides to 31250 baud, and wrote a simple
tracker-style sequencer in a mixture of C and assembler on DOS. It
worked, kind of. If you wanted to do anything really wild like change
the tempo you needed to recompile.
Gordon MM0YEQ
As for the serial card with a different crystal, BTDT, on a TRS-80 Color
Computer 3. Not only that, but the software, Ultimuse-III, written by Mike
Knudsen could handle the serial card and the bitbanger at the same time, so
I actually had 2 ports and drove two different midi keyboards each with
their own midi voice assignments. This on a machine with 60 ticks/second
IRQ's for a clock. And neither port had any extra added buffers, it Just
Worked(TM).
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
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-Ed Howdershelt (Author)
Any sufficiently advanced technology is indistinguishable from a rigged
demo.