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CPU (LSI101: MSM6387-22)
Containing a sound data ROM and a DAC (Digital to Analog Convertor), the CPU provides sound wave-
form in accodance with the pressed key and the selected tone.
The following table shows the pin functions of LSI101.
Amplifier/Voltage Regulator
(IC101: AN8053N)
The right figure shows the internal block of IC101.
AVDD
C108
Q101
2SC1740SQ
C107
AG
R107
R2106
C106
C109
AG
R105
AG
R104
R108
To power amp
From CPU
16
15
14 13
12 11
10
9
8
7
6
5
4
32
1
SP AMP
VREF
5V REG
POWER
SPO NC SP GND PC-1 PC-2 SPI SPM VREF
VCC NC CONT
5V
VREG
NCNC NC PRE GND
+
-
Filter Block
Since the sound signal from the CPU is a stepped waveform, the filter block is added to smooth the
waveform.
Pin No. Terminal In/ Out Function
1, 2 TEST1, TEST2 Not used. Connected to ground.
3 RESET In Power ON reset terminal. On: +5 V Off: 0 V
4 AVDD In +5 V sorce for the built-in DAC
5 OUT Out Sound waveform output
6 AGND In Ground (0 V) source for the built-in DAC
7 GND In Ground (0 V) source
8 COSI In 21.725 MHz clock pulse input
9 COSO Not used
10 VDD In +5 V source
11 ~ 18 KI0 ~ KI7 In Input terminals from keys and switches
19, 20 KO11, KO10 Not used
21 ~ 30 KO9 ~ KO0 Out Key and switch scan signal outputs