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CHAPTER 18 ROM Mirroring Function Selection Module
18.2
ROM Mirroring Function Selection Register (ROMM)
The ROM mirroring function select register (ROMM) enables or disables the ROM
mirroring function.When the ROM mirroring function is enabled, ROM data in the FF
bank can be read by access to the 00 bank.
I ROM Mirroring Function Select Register (ROMM)
Figure 18.2-1 ROM Mirroring Function Select Register (ROMM)
15
14
13
-
-
-
W
: Write Only
X
: Undefined
-
: Unused
: Reset Value
Table 18.2-1 Functions of ROM Mirroring Function Select Register (ROMM)
bit8
bit9
to
bit15
Note:
While the ROM area at addresses "004000
mirroring function select register (ROMM) is prohibited.
574
12
11
10
9
8
-
-
-
-
W
bit8
bit name
MI:
This bit enables or disables the ROM mirroring function.
ROM mirroring function
When set to "0": Disables ROM mirroring function
select bit
When set to "1": Enables ROM mirroring function
•
Reserved
Read: The value is undefined.
Reset Value
X X X X X X X 1
B
MI
ROM mirroring function select bit
0
Disables ROM mirroring function
1
Enables ROM mirroring function
Function
When the ROM mirroring function is enabled (MI = 1), data
at ROM addresses "FF4000
accessing addresses "004000
Be sure to set this bit to "0".
to "00FFFF
is being used, access to the ROM
"
"
H
H
" to "FFFFFF
" can be read by
H
H
" to "00FFFF
".
H
H
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