SynthModules

I wanted to have MIDI functionality in a MOTM format so I had a
Schaeffer panel made.  I also added the four CV potentiometers and
decided to add room for the Speakjet as well.  I'm still waiting for
the panel but I've made a temporary to hold the PCB and MIDI
connectors.  I've uploaded a copy of the Schaeffer file and a jpg
image at:
http://home.earthlink.net/~dabr/synths/PSIM

I've got some basic MIDI in and out code running.  I decided to start
with polled I/O until I got everything working and then migrate the
code to interrupts.

Anyone else made progress with peek and poke of the registers?  I've
found all sorts of funny stuff.  For example

a) Even though the status registers are bytes, I have to handle them
as words.  If I do bytes, setting a byte variable clobbers the next
variable.  The manual doesn't specify but it seems like peek and poke
ignore the variable size and just assume words.

b) None of the variable modifiers seem to work.  If I try to test a
bit using .bit6 then the result is 32 bits and mostly '1's.  This
doesn't make any sense.  The only way I could get it to work was to
'and' the status word with constant and test that.

Debug statements seem to take enough time that I got over run errors
on input.  The only way I could validate proper input was to transmit
it to another MIDI device and scope the waveforms.  Right now I have
a simple input filter that strips away the 'FE' status bytes.

My initial try of interrupts resulted in having to upgrade to version
7.2 to even get it to compile.  A quick first pass at interrupts
indicated that reading the data from the RDR didn't reset the
interrupt so I was immediately interrupted again. I'll be working on this next.

Dave