CHAPTER 6 BUS CONTROL
User’s Manual U14272EJ3V0UM
128
6.4 DRAM Interface
The V
R
4181 supports 16 Mbit or 64 Mbit DRAM (EDO DRAM or SDRAM). The DRAM size, type, and access
speed is set via the memory controller’s registers.
6.4.1 EDO DRAM configuration
Figure 6-7. External EDO DRAM Configuration
WE#
EDO
DRAM
Bank1
A(12:0)
D(15:0)
RAS#
UCAS#
LCAS#
MEMWR#
WE#
RAS0#
UCAS#
ADD(12:0)
DATA(15:0)
V
R
4181
EDO
DRAM
Bank0
A(12:0)
D(15:0)
RAS#
RAS1#
OE#
LCAS#
UCAS#
LCAS#
OE#
Figure 6-7 illustrates an example when connecting devices of 4 Mbits x 16.
Addresses when connecting devices of 16 Mbits or 64 Mbits are mapped as follows.
DRAM bank
Physical address (16 Mbits)
Physical address (64 Mbits)
Bank 0
0x001F FFFF to 0x0000 0000
0x007F FFFF to 0x0000 0000
Bank 1
0x003F FFFF to 0x0020 0000
0x00FF FFFF to 0x0080 0000
Remark
64 Mbit EDO DRAMs of other than 13 rows and 9 columns cannot be used with the V
R
4181.