Cpu (Msm6283-05Gs) - Casio SK 8A Service Manual & Parts List

6. CPU (MSM6283-05GS)
O
Generates Pitch and Envelope signals for Melody, Chord, Bass and Obbligato sounds,
o
Controls Keys, Switches and peripheral devices.
The following table is the pin functions of the CPU.
Pin No. Terminal Name In/Out
Function
1
BGND
5V source for internal ADC (Analog to Digital Converter)
2
VADC Ground (OV) source for internal ADC
3, 4 No function
5~11 100-106 In/Out Data bus (DO — D6)
12
AO Out
Address bus (AO)
13 107 In/Out Data bus (D7)
14 A1 Out
Address bus (A1)
15 CE Out
Chip enable signal for memory devices. LOW active.
16 —18 A2, A10, A3 Out Address bus (A2, A3, A10)
19 No function
20-29 A4—9, All-14
Out
Address bus (A4 — A9, A11 — A14)
30 A15
Out
Output enable signal for memory devices. LOW active.
31
WE
Out
Write enable signal for RAM. LOW active.
32-38 No function
39 CE1 Out Write enable signal for Percussion generator. LOW active.
40 GND 5V source
41 CE2 Out ROM pack's chip select signal. LOW active.
42
No function
43
VDD1
Ground (OV) source for internal digital circuit
44 VDD2 Ground (OV) source for internal analog circuit
45
No function
46, 47 CPI, CP2 Out ROM pack's clock pulse
48 OP Out
ROM pack's data/address change signal.
Data bus for ROM pack becomes data or address in accordance-with the
voltage level of this signal.
49-52
DO - D3 Out
Data bus for Percussion generator.
53-56
D4- D7 Out Data bus for Percussion generator and data/address bus for
ROM pack.
57, 58
OSI, OSO In/Out
7,277MHz clock pulse input 0 and output
59 Ml
In
Power ON detection signal input. HIGH active.
Receiving a pulse at Power ON, CPU starts functioning.
60 RESET
In
Reset signal input. HIGH active.
The terminal receives a pulse which resets CPU internal circuit when
new batteries or AC adaptor is set.
61
No function
62
K014 Out
Accompaniments' volume control signal.
63 K013
Out
ROM and RAM chip select signal.
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