Fujitsu MB90460 Series, Руководство по оборудованию, Страница: 604 / 739

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CHAPTER 22 ROM MIRRORING FUNCTION SELECTION MODULE
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)
Figure 22.2-1 ROM Mirroring Function Selection Register
Note:
Bank 00 accesses FF4000
H
to FFFFFF
H
from 004000
H
to 00FFFF
H
. Therefore, FFF000
H
to
FF3FFF
H
cannot be accessed even by selecting the ROM mirroring function.
Re s et v a l u e
Re s erved Re s ervedRe s erved Re s erved Re s erved Re s ervedRe s erved
XXXXXXX1
B
12 1 3 11 10 9 8
15 b it 14
R/W R/W R/W R/W R/W R/W W R/W
MI
0
1
ROM mirroring f u nction s election b it
Di sab le ROM mirroring f u nction
En ab le ROM mirroring f u nction
b it 8
Re s erved
0
Re s erved b it
Alw a y s write "0" to the s e b it s .
b it15 to b it9
X
W
R/W : Re a d ab le a nd writ ab le
: Write only
: Indetermin
a te
: Initi a l v a l u e
MI
Table 22.2-1 ROM Mirroring Function Selection Register
Bit name Function
bit15
to
bit9
Reserved bits
The read value is undefined.
Always write "0" to these bits.
bit8
MI:
ROM mirroring
function select bit
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
H
to FFFFFF
H
can be read by accessing addresses 004000
H
to 00FFFF
H
.