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14.3 Operation
When the RAME bit is set to 1, the on-chip RAM is enabled. This LSI can access the on-chip
RAM when addressing the addresses shown in Table 4-1 in each operation mode. When the
RAME bit is cleared to 0 in modes 1, 3, and 5 (expanded modes), external address space is
accessed. When the RAME bit is cleared to 0 in modes 6 and 7 (single-chip modes), the on-chip
RAM is not accessed. Read operation always reads H'FF and disables writing.
The on-chip RAM is connected to the CPU by a 16-bit wide data bus and can be read and written
on a byte or a word basis.
Byte data can be accessed in two states using the higher 8 bits of the data bus. Word data
beginning from an even address can be accessed in two states using the 16-bit data bus.
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