Yamaha PortaTone PSR-S700 Owner's Manual page 202

What is MIDI?
Finally, we'll take a look at the actual data that gets
recorded and that serves as the basis for playing the
sounds. For example, let's say you play a "C" quarter
note using the grand piano sound on the instrument's
keyboard. Unlike an acoustic instrument that puts out a
resonated note, the electronic instrument puts out infor-
mation 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
for sound generation, the tone generator plays the
stored sampled note.
Example Keyboard Data
Voice number (with what voice)
Note number (with which key)
Note on (when was it pressed)
and
note off (when was it released)
Velocity
(strength at which it was played)
Panel operations on the instrument, such as playing the
keyboard and selecting voices, are processed and
stored as MIDI data. The auto accompaniment Styles
and Songs also consist of MIDI data.
MIDI is an acronym that stands for Musical Instrument
Digital Interface, which allows electronic musical
instruments to communicate with each other, by send-
ing and receiving compatible Note, Control Change,
Program Change and various other types of MIDI data,
or messages.
The instrument can control a MIDI device by transmit-
ting note related data and various types of controller
data. The instrument can be controlled by incoming
MIDI messages which automatically determine the tone
generator mode, select MIDI channels, voices and
effects, change parameter values and of course play the
voices specified for the various parts.
n
MIDI data has the following advantages over audio data:
• The amount of data is much less.
• The data can be effectively and easily edited, even to the point
of changing voices and transforming the data.
MIDI messages can be divided into two groups: Chan-
nel messages and System messages.
Channel Messages
The PSR-S900/S700 is an electronic instrument that can
handle 16 MIDI channels (or reception of 32 channels
for MIDI data reception when using the [USB] termi-
nal). This is usually expressed as "it can play 16 instru-
ments at the same time." Channel messages transmit
information such as Note ON/OFF, Program Change,
for each of the 16 channels.
202 PSR-S900/S700 Owner's Manual
01 (grand piano)
n
60 (C3)
The performance data of all Songs and Styles is handled as MIDI
Timing expressed
data.
numerically
(quarter note)
MIDI Channels
MIDI performance data is assigned to one of sixteen
120 (strong)
MIDI channels. Using these channels, 1–16, the perfor-
mance data for sixteen different instrument parts can be
simultaneously sent over one MIDI cable.
Think of the MIDI channels as TV channels. Each TV
station transmits its broadcasts over a specific channel.
Your home TV set receives many different programs
simultaneously from several TV stations and you select
the appropriate channel to watch the desired program.
MIDI operates on the same basic principle. The trans-
mitting instrument sends MIDI data on a specific MIDI
channel (MIDI Transmit Channel) via a single MIDI
cable to the receiving instrument. If the receiving instru-
ment's MIDI channel (MIDI Receive Channel) matches
the Transmit Channel, the receiving instrument will
sound according to the data sent by the transmitting
instrument.
MIDI Transmit channel 2
n
The instrument's keyboard and internal tone generator are also
connected by MIDI. → LOCAL CONTROL (
For example, several parts or channels can be transmit-
ted simultaneously, including the Style data (as shown
on the next page).
Message Name Operation/Panel Setting
Messages which are generated when
Note ON/OFF
the keyboard is played. Each mes-
sage includes a specific note num-
ber which corresponds to the key
which is pressed, plus a velocity
value based on how hard the key is
played.
For selecting Voices (with control
Program Change
change bank select MSB/LSB set-
tings)
Control Change Volume, panpot (Mixing Console),
MODULATION Wheel operation
etc.
Pitch Bend PITCH BEND Wheel operation
Weather report
NEWS
1
2
MIDI
cable
2
NEWS
MIDI Receive channel 2
page 207
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