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M16C/62P Group (M16C/62P, M16C/62PT)
9. Memory Space Expansion Function
Note
9. Memory Space Expansion Function is described in the M16C/62P (128-pin version and
100-pin version) only as an example.
The M16C/62P (80-pin version) and M16C/62PT do not use this function.
The following describes a memory space extension function.
During memory expansion or microprocessor mode, the memory space expansion function allows the
access space to be expanded using the appropriate register bits.
Table 9.1 shows the way of setting memory space expansion function, memory spaces.
Table 9.1 The Way of Setting Memory Space Expansion Function, Memory Space
Memory Space Expansion Function How to Set (PM15 to PM14)
1-Mbyte Mode
4-Mbyte Mode
9.1 1-Mbyte Mode
In this mode, the memory space is 1 Mbytes. In 1-Mbyte mode, the external area to be accessed is
specified using the CSi (i = 0 to 3) signals (hereafter referred to as the CSi area). Figures 9.2 to 9.3 show
the memory mapping and CS area in 1-Mbyte mode.
9.2 4-Mbyte Mode
In this mode, the memory space is 4 Mbytes. Figure 9.1 shows the DBR register. The BSR2 to BSR0 bits
in the DBR register select a bank number which is to be accessed to read or write data. Setting the OFS bit
to "1" (with offset) allows the accessed address to be offset by 40000h.
In 4-Mbyte mode, the CSi (i=0 to 3) pin functions differently for each area to be accessed.
9.2.1 Addresses 04000h to 3FFFFh, C0000h to FFFFFh
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• The CSi signal is output from the CSi pin (same operation as 1-Mbyte mode. However the last
address of CS1 area is 3FFFFh)
9.2.2 Addresses 40000h to BFFFFh
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• The CS0 pin outputs "L"
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• The CS1 to CS3 pins output the value of setting as the BSR2 to BSR0 bits (bank number)
Figures 9.4 to 9.5 show the memory mapping and CS area in 4-Mbyte mode. Note that banks 0 to 6 are
data-only areas. Locate the program in bank 7 or the CSi area.
R
e
. v
2
3 .
0
S
e
p
0
, 1
2
0
0
4
R
E
J
0
9
B
0
1
8
5
0 -
2
3
0
Z
______
_____
______
_______
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page 57
f o
3
6
4
9. Memory Space Expansion Function
00b
11b
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______
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Memory Space
1 Mbyte (no expansion)
4 Mbytes
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