Casio CTK-411 Service Manual page 6

CPU (LSI1: MSM6755C-17)
The CPU reads sound data from the ROM in accordance with the pressed key and the selected tone; the CPU
can read rhythm data simultaneously when a rhythm pattern is selected. Then it provides the left and the right
channels' waveforms separately, by converting the data into the waveforms with two built-in DACs. The CPU
also controls key and button input. The following table shows the pin functions of LSI1.
Pin No. Terminal
1 MA14
2, 3 NCO
4 ~ 19 MA0 ~ MA13
13 MRDB
17 MCSB
20 ~ 27 MD0 ~ MD7
28, 29 NC1, NC2
30 DGND
31 DVCC
32, 33 XTLO, XTLI
34 NC3
35 RSTB
36 P24/RXD
37 P25/TXD
38 NMI
39 APO
40 NC4
41 REFH
42, 43 NC5, NC6
44 DAOR
45 NC7
46 AVdac
47 DAOL
48 REFL
49 AGdac
50 AGadc
51 ANI
52 AVadc
53 NC8
54 MOD0
55, 56 MOD1, MOD2
57 P40
58 ~ 64 KI0/P30 ~ KI7/P36
65 KI7/P37
66 ~ 73 KO0/P50 ~ KO7/P57
In/Out
Out Address bus
— Not used
Out Address bus
Out Read enable signal
— Not used
In/Out Data bus
— Not used
In Ground (0 V) source
In +5 V source
In/Out 20 MHz clock input/output
— Not used
In Reset signal input
— MIDI signal input
— MIDI signal output
In Power ON signal input. Connected to +5 V.
Out APO (Auto Power Off) signal output
— Not used
Out Terminal for the internal DAC
— Not used
Out Sound waveform signal output
— Not used
In +5 V source for the internal DAC
Out Left channel sound waveform output
Out Terminal for the internal DAC and ADC
In Ground source for internal DAC
In Ground source for internal ADC
In Not used
In +5 V source for the internal ADC
— Not used
In Mode selection terminal. Connected to +5 V.
In Mode selection terminal. Connected to ground.
— Not used
In Terminals for key/button input signal
— Not used
Out Terminals for key scan signal
— 4 —
Function