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27.2
ROM Mirroring Register (ROMM)
Do not access the ROM mirroring register (ROMM) when addresses "004000
"00FFFF
" are being accessed.
H
■ ROM Mirroring Register (ROMM)
Address:
00006F
R/W
:
Readable and writable
W
:
Write only
X
:
Undefined value
-
:
Undefined
Table 27.2-1 Function of Each Bit of ROM Mirroring Register
Bit name
bit15 to
Undefined
bit10
MS:
bit9
Mirror size
MI:
bit8
Mirror bit
Note:
Only "FF4000
the ROM mirroring function is activated. Therefore, addresses "FF0000
will not be mirrored to 00 bank.
Figure 27.2-1 ROM Mirroring Register (ROMM)
bit
15
14
13
12
11
-
-
-
-
-
H
-
-
-
-
-
"1": The ROM mirror size is 32K Bytes (008000
"0": The ROM mirror size is 48K Bytes (004000
Note:
This bit is fixed to "1" and read only in the MB90V390H, MB90V390HA, and
MB90F390HB.
In MB90394HA and MB90F394H(A) it is selectable.
The image of the ROM data in the FF bank can also be found in the 00 bank when "1" is
written to this bit. However, this memory mapping will not be done when this bit is
written to "0". This bit is write only.
"/"FF8000
" to "FFFFFF
H
H
CHAPTER 27 ROM MIRRORING MODULE
ROMM
10
9
8
Initial value
-
MS MI
X X X X X X + 1
(+): MB90V390H: read only, fixed to "1"
-
R/W W
MB90F394H: selectable; initial value "0"
(+)
Function
" is mirrored to "004000
H
B
−
to 00FFFF
)
H
H
to 00FFFF
)
H
H
"/"008000
" to "00FFFF
H
H
" to "FF3FFF
H
" to
H
" when
H
"/"FF7FFF
"
H
H
553
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