Roland U-20 Owner's Manual page 88

2.
MIDI Data
Used by the U-20
(Pitch
Bender
•Aftertouch
Pitch
bender messages transmit
the position of
the pitch
bender
lever.
Only the position
of
the lever
is
transmitted,
meaning
that the actual pitch
change (bend range) will
depend on the settings of
the
somid
generator. In the
U-20, the pitch
bend range
is
determined
by
a
Timbre
or
Rhythm
Set
parameter.
Aftertouch data transmits the force
with
which you
press
down
on the
keyboard after
playing a
note.
The
effect
this will
have depends on
the settings
of
the
soimd
generator.
Aftertouch
is
divided into
"channel aftertouch"
and "polyphonic
aftertouch".
Channel
aftertouch transmits a
single
aftertouch value
telling
the
pressure
of
the
key being
pressed
most
strongly,
and
affects
the entire
MIDI channel.
Polyphonic aftertouch transmits an aftertouch
value
for
each
key, telling
how
strongly
each
key
is
being pressed.
This allows
you
to individually control the
sound
of
each
note being pressed,
even
within a single
MIDI
channel.
The
U-20's
so;md
generator responds
to
both types
of
aftertouch,
but only channel aftertouch
can be controlled
from the U-20's
keyboard.
System Messages
System
messages
are
used to control
all
devices in the entire
MIDI-connected system,
regardless of their
channel
number.
In addition to exclusive
messages (explained
below),
system messages
include various types of
message used by sequencers,
and messages
that help the
system keep running properly.
•Exclusive
Messages
Exclusive
messages
carry data imique
to
each
device,
such
as
data for a
device's internal
memory.
Normally, they
are transmitted
and received only
between devices
of
the
same
type
made by
the
same manufacturer.
For example,
you can use exclusive
messages
to
transmit
U-20
Timbre
or
Patch data
to
another U-20, or
to store
U-20
Timbre
or
Patch data
in
a sequencer.
86