10.3 RAM Enable Bit (RAME) in System Control Register (SYSCR)
The on-chip RAM is enabled or disabled by the RAME (RAM Enable) bit in the system control
register (SYSCR).
Bit
7
6
5
4
3
2
1
0
SSBY
STS2
STS1
STS0
—
NMIEG
—
RAME
Initial value
0
0
0
0
1
0
1
1
Read/Write
R/W
R/W
R/W
R/W
—
R/W
—
R/W
The only bit in the system control register that concerns the on-chip RAM is the RAME bit. See
section 2.2, “System Control Register” for the other bits.
Bit 0—RAM Enable (RAME): This bit enables or disables the on-chip RAM.
The RAME bit is initialized to “1” on the rising edge of the RES signal, so a reset enables the on-
chip RAM. The RAME bit is not initialized in the software standby mode.
Bit 7
RAME
Description
0
On-chip RAM is disabled.
1
On-chip RAM is enabled.
(Initial value)
10.4 Operation
10.4.1 Expanded Modes (Modes 1 and 2)
If the RAME bit is set to “1,” accesses to addresses H'FB80 to H'FF7F in the H8/329 and H8/328,
addresses H'FD80 to H'FF7F in the H8/327, and addresses H'FE80 to H'FF7F in the H8/326 are
directed to the on-chip RAM. If the RAME bit is cleared to “0,” accesses to these addresses are
directed to the external data bus.
10.4.2 Single-Chip Mode (Mode 3)
If the RAME bit is set to “1,” accesses to addresses H'FB80 to H'FF7F in the H8/329 and H8/328,
addresses H'FD80 to H'FF7F in the H8/327, and addresses H'FE80 to H'FF7F in the H8/326 are
directed to the on-chip RAM.
If the RAME bit is cleared to “0,” the on-chip RAM data cannot be accessed. Attempted write
access has no effect. Attempted read access always results in H'FF data being read.
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