Roland sh-101 Service Manual page 5

SH-101
5.
KEYBOARD READ
The
CPU
uses
a
4
x
8 matrix
to
read the
number
and
position of
the keys being
pressed
on
the keyboard,
and determines
the
output
priority of
the
CV
data
and
whether
new
Gate
signal
should be output according
to
the key
mode
(LEGATO
or
NON-LEGATO)
and
the
set-
tings of the panel controls
(PORTAMENTO, ARPEG-
GIO,
GATE
/TRIG,
etc.)
6.
CLOCK CHECK
Any
variation
in
the voltage
of
the Clock
signal
(LFO
or
EXT
C LK
)
is
detected
at
the T1 terminal
.
If
a
low Clock
signal turns high,
TR1
1
inverts
it
to
low and
sends
it
to
the
CPU,
which
then
performs
the following operations.
(a)
Generates
Random
data.
(b)
Prepares the
data for
Arpeggio and Sequencer
playing.
7.
RANDOM
DATA OUTPUT
The
CPU
outputs
to
the
D/A
Converter
the
random
data
generated
and
stored
in
step 6(a).
8.
FUNCTION SWITCH READ
The
CPU
scans
all
the function switches
in
order to
detect any changes
made
by
the user.
If
an
On/Off
change
is
detected, the
CPU
jumps
to
the appropriate
step.
Refer
to the
flow
chart.
The CPU
can detect the
On/Off
status of the
HOLD
function
at
both
the Panel button
and
the Pedal switch.
When
the
KEY TRANSPOSE
button
is
pressed
and
a
new
key
selected, the
CPU
iden-
tifies
the
key
that
was
pressed on the
keyboard and
thus
identifies
the key
(pitch) to
be transposed.
9.
LOAD
If
a
Keyboard
key, the
LEGATO
(HOLD)
button
or
the
REST
(KEY
TRANSPOSE)
button
is
pressed, the
CPU
stores that information
in
the
RAM,
then
jumps
to step
12.
If
no key
or
button
is
pressed, the
CPU
jumps
directly to step
1
2.
10.
PLAY
In the Play
mode,
the
CPU
reads the Sequencer
data
stored
in
the
RAM
and
prepares both the
KCV
and Gate
data, then
jumps
to
step
1
2.
11.
ARPEGGIO
If
the
CPU
detects
during
step
6 that the Clock
signal
has
turned
high, the
CPU
prepares the
KCV
data accord-
ing to
the order of the key
numbers
stored
in
the 4-byte
(32 keys) Arpeggio
Key
Buffer,
then
jumps
to step 12.
If
the Clock
Signal
remains low, the
CPU
jumps
directly
to step
1
2.
12.
CV OUTPUT
During the Arpeggio and Sequencer
Play
modes,
the
CPU
sends
to
the
D/A
Converter the necessary
CV
data
for
executing the
relevant
steps
for
Arpeggio
or
Sequencer
playing.
During
all
other modes, the
TRANSPOSE
Switch data
(L,
M
or
H
)
is
either
added
to
or
subtracted
from
the
Keyboard
information,
and
the
resulting value
is
sent
to
the
D/A
Converter.
Examples
of
this
operation are
shown
below.
Transpose Switch
Position
Key
CV
Data (After
D/A
Conversion)
L
Lowest
F
0.417V
M
Lowest
F
1.417V
H Lowest
F
2.417V
H
Highest
C
5.0V
13.
GATE
& LED
DATA OUTPUT
Port 2
of
the
CPU
outputs the Gate, Clock Reset
(CLK
RST)
and
LED
Illumination
signals.
The
Clock Reset
signal resets
the
Clock
signal
whenever
a
key on
the key-
board
is
pressed while
either
the
GATE/TRIG
Selector
is
set to
LFO
or
the
ARPEGGIO
mode
is
activated.
The
LED
Illumination
signal
illuminates the
LEDs
above the
function switches, but
does
not illuminate the
LEDs
for
the
LFO
and powerswitches.
At
the
end
of
step
1 3,
the
CPU
returns
to
program
3
and
repeats the
sequence
of steps
from 3 through 13.
• PIN
CONNECTION
(Top View)
TMP80C49P
TOE
1
40
VCC(+5V}
XTAL1
E
2
39
ti
XTAL2E
3 38
P27
resetE
4 37
P26
ss
5
36
P25
INT
6 35
P24
EA
7 34
P17
rdE
8 33
P16
PSEN
E
9 32
E|P15
WR
E
10 31
p14
ALE
E
11
30
E|P13
dboE
12 29
E|P12
DB1
13
28
pi
1
DB2E
14 27
E|P10
DBS
15
26
PS
dbaE
16 25
prog
DB5E
17
24
P23
DB6
18 23
P22
DB7
19
22
P21
SS(0V)E
20 21
P20