HD6413002 Datasheet, PDF (516/700 Pages) Renesas Technology Corp – High-performance single-chip microcontroller

One function of SYSCR is to enable or disable access to the on-chip RAM. The on-chip RAM is
enabled or disabled by the RAME bit in SYSCR. For details about the other bits, see section 3.3,
System Control Register.
Bit 0—RAM Enable (RAME): Enables or disables the on-chip RAM. The RAME bit is
initialized at the rising edge of the input at the RES pin. It is not initialized in software standby
mode.
Bit 0
RAME
0
1
Description
On-chip RAM is disabled
On-chip RAM is enabled
(Initial value)
15.3 Operation
When the RAME bit is set to 1, accesses to addresses H'FFD10 to H'FFF0F in modes 1 and 2, and
to addresses H'FFFD10 to H'FFFF0F in modes 3 and 4, are directed to the on-chip RAM. When
the RAME bit is cleared to 0, the off-chip address space is accessed.
Since the on-chip RAM is connected to the CPU by an internal 16-bit data bus, it can be written
and read by word access. It can also be written and read by byte access. Byte data is accessed in
two states using the upper 8 bits of the data bus. Word data starting at an even address is accessed
in two states using all 16 bits of the data bus.
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