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22.2
ROM Mirroring Function Selection Register (ROMM)
The ROM mirroring function selection register (ROMM) is used to enable mirroring
function.
■ ROM Mirroring Function Selection Register (ROMM)
bit
15
14
13
Reserved ReservedReservedReservedReserved ReservedReserved
R/W
R/W
R/W
R/W : Readable and writable
W
: Write only
: Indeterminate
X
: Initial value
Table 22.2-1 ROM Mirroring Function Selection Register
Bit name
bit15
to
Reserved bits
bit9
MI:
bit8
ROM mirroring
function select bit
Note:
Bank 00 accesses FF4000
FF3FFF
cannot be accessed even by selecting the ROM mirroring function.
H
CHAPTER 22 ROM MIRRORING FUNCTION SELECTION MODULE
Figure 22.2-1 ROM Mirroring Function Selection Register
12
11
10
9
8
MI
R/W
R/W
R/W
R/W
W
bit8
MI
bit15 to bit9
Reserved
The read value is undefined.
Always write "0" to these bits.
This bit enables or disables the ROM mirroring function.
When set to "0": Disables ROM mirroring function
When set to "1": Enables ROM mirroring function
When the ROM mirroring function is enabled (MI = 1), data at ROM addresses
FF4000
to FFFFFF
H
to FFFFFF
H
Reset value
XXXXXXX1
B
ROM mirroring function selection bit
0
Disable ROM mirroring function
1
Enable ROM mirroring function
Reserved bit
0
Always write "0" to these bits.
Function
can be read by accessing addresses 004000
H
from 004000
H
H
to 00FFFF
H
to 00FFFF
.
Therefore, FFF000
H
.
H
to
H
585
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