JVC KB-700 Service Manual page 4

B-700 B/N/H
Outline of Microcomputer in This Keyboard
1. Main functions of microcomputers
• Keying of orchestra presets
(including sound source dividing function)
• Sound source dividing for solo presets
• Fascinating chord
• Auto-rhythm
• Selecting of presets and effects
• compucorder
• Key transpose
• Ultrachord
• Key split
• Turning on and off of LEDs
2. Block diagram
Rhythm pulse
Key pulse (UKP)
Backing pulse
Glide control pulse Solo synthe se|ect
Fig. 2
3. 1C terminals
■ CPU
MSM80C49-40RS (2
K bites ROM, 128 bites RAM, 8-bit 1-chip type) CPU controls all operations according to
the programs of the built-in ROM and an
Power source
Ceralock j:-
for clock 5=
Reset by
input L
Rhythm
tempo IN
Outputs
for ROM
and RAM
controls
Composite
ports
Data
bus
T 0
1
40 +
5
V
F
X 1
2
39
T l
X 2
3
38 P2- 7
RES
4
37 P2- 6
s s
5
36 P2-5
HTt
6
35
P2- 4
E A
34
PI-7
To
8
33
PI- 6
PSEN
9
32
P 1 - 5
w"r
10
31
PI - 4
ALE
1 1
30 PI - 3
D 8 ®
12
29
PI- 2
OBI
13
28
PI - 1
0 B 2
14
27
P l- *
0 B 3
15
26 + 5 V
0 B4
16
25
PRO G
0 B 5
17
24 P2 - 3
D 8 6
18
23 P2-2
■
0 8 7
19
22
P2 - 1
G N 0
' 20
21
P2- »
additional ROM (MSM83C55).
-.J Data output for POTS
Port 2
Solo synthe. key pulse
Piano/guitar switchover
Port 1
Input
Switch ON data of Manual key.
Fascinating, Auto-rhythm, Presets, etc.
Port 2
Output for
ROM & RAM controls
Fig. 3
4