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• When OC index mode is off (CCR.OIX = 0)
H'7C00 0000 to H'7C00 0FFF (4 kB): Corresponds to RAM area 1
H'7C00 1000 to H'7C00 1FFF (4 kB): Corresponds to RAM area 1
H'7C00 2000 to H'7C00 2FFF (4 kB): Corresponds to RAM area 2
H'7C00 3000 to H'7C00 3FFF (4 kB): Corresponds to RAM area 2
H'7C00 4000 to H'7C00 4FFF (4 kB): Corresponds to RAM area 1
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RAM areas 1 and 2 then repeat every 8 kbytes up to H'7FFF FFFF.
Thus, to secure a continuous 8-kbyte RAM area, the area from H'7C00 1000 to H'7C00 2FFF
can be used, for example.
• When OC index mode is on (CCR.OIX = 1)
H'7C00 0000 to H'7C00 0FFF (4 kB): Corresponds to RAM area 1
H'7C00 1000 to H'7C00 1FFF (4 kB): Corresponds to RAM area 1
H'7C00 2000 to H'7C00 2FFF (4 kB): Corresponds to RAM area 1
:
H'7DFF F000 to H'7DFF FFFF (4 kB): Corresponds to RAM area 1
H'7E00 0000 to H'7E00 0FFF (4 kB): Corresponds to RAM area 2
H'7E00 1000 to H'7E00 1FFF (4 kB): Corresponds to RAM area 2
:
H'7FFF F000 to H'7FFF FFFF (4 kB): Corresponds to RAM area 2
As the distinction between RAM areas 1 and 2 is indicated by address bit [25], the area from
H'7DFF F000 to H'7E00 0FFF should be used to secure a continuous 8-kbyte RAM area.
4.3.7
OC Index Mode
Setting CCR.OIX to 1 enables OC indexing to be performed using bit [25] of the effective
address. This is called OC index mode. In normal mode, with CCR.OIX cleared to 0, OC indexing
is performed using bits [13:5] of the effective address. Using index mode allows the OC to be
handled as two 8-kbyte areas by means of effective address bit [25], providing efficient use of the
cache.
Rev. 4.0, 04/00, page 70 of 850
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