Yamaha PSR-270 - Manual (Page 93)

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MIDI FUNCTIONS
The PortaTone is MIDI-compatible, featuring MIDI IN and MIDI OUT terminals
and providing a variety of MIDI-related controls. By using the MIDI functions
you can expand your musical possibilities. This section explains what MIDI is, and
what it can do, as well as how you can use MIDI on your PSR-270.
WHAT IS MIDI?
No doubt you have heard the terms “acoustic instrument” and “digital instrument.” In the world
today, these are the two main categories of instruments. Let’s consider an acoustic piano and a classi-
cal guitar as representative acoustic instruments. They are easy to understand. With the piano, you
strike a key, and a hammer inside hits some strings and plays a note. With the guitar, you directly
pluck a string and the note sounds. But how does a digital instrument go about playing a note?
As shown in the illustration above, in an electronic instrument the sampling note (previously recorded
note) stored in the tone generator section (electronic circuit) is played based on information received
from the keyboard. So then what is the information from the keyboard that becomes the basis for
note production?
For example, let’s say you play a “C” quarter note using the grand piano sound on the PSR-270
keyboard. Unlike an acoustic instrument that puts out a resonated note, the electronic instrument puts
out information from the keyboard such as “with what voice,” “with which key,” “about how strong,”
“when was it pressed,” and “when was it released.” Then each piece of information is changed into a
number value and sent to the tone generator. Using these numbers as a basis, the tone generator
plays the stored sampling note.
Voice number (with what voice) 01 (grand piano)
Note number (with which key) 60 (C3)
Note on (when was it pressed) and Timing expressed numerically (quarter note)
note off (when was it released)
Velocity (about how strong) 120 (strong)
Example of Keyboard Information
Acoustic guitar note production Digital instrument note production
Pluck a string and the body
resonates the sound. Based on playing information from the keyboard, a
sampling note stored in the tone generator is
played through the speakers.
L R Tone Generator
(Electronic circuit) Sampling
Note
Playing the keyboard
Sampling
Note
The MIDI functions cannot be used in the Song mode.
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