E-Mu SP1200 Bedienungsanleitung PDF herunterladen (Seite 78)

APPENDIX

F#. However, note that the computer doesn’t care whether this word isplaced on the data

bus due to closing a keyboard switch or striking a drum head — once MIDI translates a

note into computer language, the note becomes compatible with any device that speaks the

same language. MIDI provides access to the computer’s data bus and selects which device

will be “on the bus” at any 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 incompat-

ible devices will be able to communicate with each other over a common data bus.

How does MIDI differentiate between different MIDI instruments on the same

bus?

MIDI provides 16 independent channels of information suitable for driving up to 16 poly-

phonic synthesizers or other MIDI devices. There are three modes that determine how each

MIDI instrument responds to these channels.

In Omni mode, the SP-1200 (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 synthe-

sizers. Therefore, mono mode is not implemented in the SP-1200.

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 instru-

ment 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, hope-

fully 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.

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E-Mu SP1200 Bedienungsanleitung Seite 78