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M30245 Group
4.3.5 Chip Selects and Address Bus
When there are insufficient chip select signals, it is necessary to generate chip selects externally. Figure
4.3.6 shows an example of a connection in which the CS2 (128K bytes) area is divided into four 32K byte
areas.
M i c r o c o m p u t e r
C N V
W R
S S
R D
A
t o A
0
1 7
B Y T E
C S 2
D
t o D
0
7
M e m o r y m a p
00000
16
∼ ∼
0 8 0 0 0
1 6
0FFFF
16
10000
16
1 7 F F F
1 6
1 8 0 0 0
1 6
1 F F F F
1 6
20000
16
2FFFF
16
3 0 0 0 0
1 6
∼ ∼
F F F F F
1 6
Figure 4.3.6. Chip selects and address bus
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
A
1 5
1
1 6
A
16
2
Y 1
A
1 7
3
1 4
Y 2
4
13
Y 3
5
1 2
Y4
6
1 1
8
7 4 H C 1 3 8
∼ ∼
I C 0
IC1
C S 2
I C 2
I C 3
∼ ∼
page 339 of 354
_______
I C 0
A
9
1
2 8
A
8
2
2 7
A
A
7
1 0
3
2 6
A
A
6
1 1
4
25
A
A
5
1 2
5
2 4
A
A
4
13
6
2 3
A
3
7
2 2
A
A
2
1 4
8
21
A
Y
1
1
9
20
A
D
0
7
1 0
1 9
D
D
0
6
1 1
1 8
D
D
1
5
12
17
D
D
2
4
13
16
D
3
1 4
1 5
M5M5278
4. External Buses
I C 3
A
t o A
0
1 4
• • •
Y
D
to D
0
7
M5M5278
4
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