wolpert@hpislx.HP.COM (David Wolpert) (07/27/88)
I finally found time to build (and test) the level converters necessary
to get my Model 100 to speak MIDI. Next question: how do I get it to
_hear_ MIDI? I figured out how to change the baud rate, and now I can
play tunes on my piano. But when I try to send stuff from the piano
keyboard to the computer, all I get is zeroes or 255's. I think when I
try to do an INPUT$, the baud rate changes back to 9600 or something;
and if I try to read the UART port directly, the byte has already been
taken away by the interrupt processing (RST 6.5, I think).
So where does the interrupt routine put the byte it gets from the serial
port? Is this info somewhere in the technical reference manual? Do I
need to replace the interrupt routine with one of my own? Does somebody
have commented listings of the firmware? Is there a book I can buy that
tells me all this? Or, better yet, has anybody done a cheap Model 100
MIDI library for Ensoniq/Yamaha/Roland/etc.?
By the way, the hardware to do this was pretty simple: an optoisolator, a
couple of diodes, some resistors, a MIDI cable and a DB25 connector. The
"electronics" is wired on a small PC prototype board that fits inside the
connector shell, so it even looks nice. The output current is only about
one milliamp (MIDI spec is five, I think), but it works with every MIDI
synthesizer I've tried (yeah, I know, probably not at 40 deg/95 pct; if I
were doing this as an HP product, it would have to have batteries :-).
Any help is appreciated; maybe I can return the favor. Thanks in advance.
-- _ _
/ \/ \ David Wolpert (303) 679-3533
/_ __ HEWLETT \ / Measurement Systems Operation
/ / /_/ PACKARD \ / Box 301 - Loveland, CO 80539
/ \/ wolpert%hpisla@hplabs.HP.COM
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"Be joyful always; pray continually; give thanks in all circumstances"oster@dewey.soe.berkeley.edu (David Phillip Oster) (08/15/88)
See "Inside the TRS-80 Model 100" by Carl Oppendahl,
$19.95 from Weber Systems, Inc.
8437 Maysfield Road,
Chesterland, Ohio, 44026
for details on the serial drivers in the Model 100.
Sounds like an interesting project. I can see downloading a patch library
and a set of sequences from your main computer so you'll have them ready
for a gig.
--- David Phillip Oster --When you asked me to live in sin with you
Arpa: oster@dewey.soe.berkeley.edu --I didn't know you meant sloth.
Uucp: {uwvax,decvax,ihnp4}!ucbvax!oster%dewey.soe.berkeley.edu