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CPU
LSI101
UPD912GF-3BA
Sound Source ROM
LSI102
MX23C8100PC-12CA19
CE
A0 ~ A18
D0 ~ D15
MA1 ~
MA19
MD0 ~
MD15
MSB0
FI0 ~ FI7
SI0 ~ SI7
SO
BOK
LRCK
PG
X101
20 MHz
DAC
IC103
UPD6379GR
LOUT
ROUT
SO: Sound data
BOK: Bit clock
LRCK: Word clock
SI
CLK
LRCK
From keyboard
Reset IC
IC104
RE5VA35AA
Power Supply Circuit
VDD
Battery set
RESET
VDD
POWER
From power switch
NMI
APO
CPU
LSI101
UPD912GF-3BA
SCKO
NOMENCLATURE OF KEYS
RESET CIRCUIT
When batteries are set or an AC adapter is connected, the reset IC provides a low pulse to the CPU. The CPU
then initializes its internal circuit.
When the power switch is pressed, the CPU receives a low pulse of POWER signal.The CPU raises APO signal
to +5 V to turn power on.
CPU (LSI101: UPD912GF-3BA)
The 16-bit CPU contains a 1k-byte RAM, three 8-bit I/O ports, two timers, a keycontroller and serial interfaces.
The CPU detects key velocity by counting the time between first-key input signal FI and second-key SI from
the keyboard. The CPU reads sound data and velocity data from the sound source ROM in accordance with
the selected tone; the CPU can read rhythm data simultaneously when a rhythm pattern is selected. Then the
CPU provides 16-bit serial sound data to the DAC.The CPU also controls MIDI input/output and LED driving.
F#3 G#3 A#3
C#4 D#4
F#4 G#4 A#4
C#5 D#5
F#5 G#5 A#5
F3
G3
A3
B3
C4
D4
E4
F4
G4
A4
B4
C5
D5
E5
F5
G5
A5
B5
C6
D#3
C2
D2
E2
F2
G2
A2
B2
C3
D3
E3
B6
A6
G6
F6
E6
D6
C7
C#3
A#2
G#2
F#2
D#2
C#2
A#6
G#6
F#6
D#6
C#6
