SP Studio Systems SP-12 - Manual (Page 91)

APPENDIX
© E-mu Systems, Inc. 1985 Page 91
Enhanced by The Emulator Archive 2002 www.emulatorarchive.com
particular moment, thus letting you determine the flow of information from one
MIDI device to another. This is why having a specification which
manufacturers can follow is so important; it insures that a variety of otherwise
incompatible devices will be able to communicate with each other over a
common data bus.
How does MIDI differentiate between different instruments?
MIDI provides 16 independent channels of information suitable for driving up to 16
polyphonic synthesizers or other MIDI devices. There are three modes that
determine bow each MIDI instrument responds to these channels.
In Omni mode, the SP-12 (or any other MIDI device) listens to all channels at once.
No matter how many notes from how many sources make it through the MIDI bus
into the instrument, when in Omni mode it will attempt to play all of them.
In Poly mode, the instrument can “tune in” to one MIDI channel --just like you can
tune in one channel of your television. Having a bunch of’ instruments set to Poly
mode lets you send specific information to different instruments over different MIDI
channels.
Mono mode is considered a “multi-timbral” mode that is applicable to multi-voice
synthesizers. Therefore, mono mode is not implemented in the SP-12.
16 channels, huh? Sounds like a lot of patch cords to me!
MIDI information is transmitted serially, meaning that all data is sent in sequence. As
a result, a single line can carry the MIDI information for all 16 channels, with each
instrument monitoring all the words that pass over the MIDI interface but responding
only to the data on its particular channel. Typically, MIDI instruments include a MIDI
IN, MIDI OUT, and MIDI THRU jack. The instrument receives data over the MIDI IN
jack and transmits data over the MIDI OUT jack; the MIDI THRU jack provides a
replica of the signal at the MIDI IN jack. Therefore, if’ you want to slave three MIDI
devices to a master MIDI device, you would patch the MIDI OUT from the master to
the MIDI IN of the first slave, patch MIDI THRU from the first slave to the MIDI IN of
the second slave, and connect MIDI THRU from the second slave to MIDI IN of the
third slave.
What kind of words does the MIDI language include?
Spoken language is a collection of words that convey a particular set of meanings,
hopefully understood by all those who speak the language. As soon as we start
talking about a musical language, the first question is: What concepts do we want
this language to define? Since musical instruments will be doing the talking, the
language should consist of’ musical terms -- pitch, tempo, and so
on.