HD6475328CG Datasheet, PDF (305/459 Pages) Hitachi Semiconductor – Manual Gives a Hardware Description

16.1.2 Register Configuration
The on-chip RAM is controlled by the register described in table 16-1.
Table 16-1 RAM Control Register
Name
Abbreviation R/W
RAM control register RAMCR
R/W
Initial Value
H'FF
Address
H'FFF9
16.2 RAM Control Register (RAMCR)
Bit
7
6
5
4
3
2
1
0
RAME —
—
—
—
—
—
—
Initial value
1
1
1
1
1
1
1
1
Read/Write
R/W
—
—
—
—
—
—
—
The RAM control register (RAMCR) is an 8-bit register that enables or disable the on-chip RAM.
Bit 7—RAM Enable (RAME): This bit enables or disables the on-chip RAM.
The RAME bit is initialized on the rising edge of the signal. It is not initialized in the software
standby mode.
Bit 7
RAME
0
1
Description
On-chip RAM is disabled.
On-chip RAM is enabled.
(Initial value)
Bits 6 to 0—Reserved: These bits cannot be modified and are always read as 1.
16.3 Operation
16.3.1 Expanded Modes (Modes 1, 2, 3, and 4)
If the RAME bit is set to 1, accesses to addresses H'FB80 to H'FF7F are directed to the on-chip
RAM. If the RAME bit is cleared to 0, accesses to addresses H'FB80 to H'FF7F are directed to
the external data bus.
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