Figure 13.3 External Memory Space Allocation - Hitachi SH7751 Hardware Manual

Area 0: H'00000000
Area 1: H'04000000
Area 2: H'08000000
Area 3: H'0C000000
Area 4: H'10000000
Area 5: H'14000000
Area 6: H'18000000
Memory Bus Width: In the SH7751 Series, the memory bus width can be set independently for
each space. For area 0, a bus size of 8, 16, or 32 bits can be selected in a power-on reset by means


of the pin, using external pins. The relationship between the external pins (MD4 and
MD3) and the bus width in a power-on reset is shown below.
MD4 MD3
0 0
1
1 0
1
When SRAM interface or ROM is used in areas 1 to 6, a bus width of 8, 16, or 32 bits can be
selected with bus control register 2 (BCR2). When burst ROM is used, a bus width of 8, 16, or 32
bits can be selected. When byte control SRAM interface is used, a bus width of 16, or 32 bits can
be selected. When the MPX interface is used, a bus width of 32 bit can be set. When the DRAM
interface is used, a bus width of 16, or 32 bits can be selected with the memory control register
(MCR). For the synchronous DRAM interface, set a bus width of 32 bit in the MCR register.
When using the PCMCIA interface, set a bus width of 8 or 16 bits. For details, see section 13.3.7,
PCMCIA Interface.
SRAM/burst ROM/MPX
SRAM/MPX/byte control SRAM
SRAM/synchronous DRAM/MPX
SRAM/synchronous DRAM/DRAM/
MPX
SRAM/MPX/byte control SRAM
SRAM/burst ROM/PCMCIA/MPX
SRAM/burst ROM/PCMCIA/MPX

Figure 13.3 External Memory Space Allocation

Bus Width
Reserved
8 bits
16 bits
32 bits
The PCMCIA interface is
for memory and I/O card use
Rev. 3.0, 04/02, page 313 of 1064