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4.10 DRAM Control Register 4/5 (DMCR4/5)
[bit 4] REFE (REFresh Enable bit)
The REFE bit specifies whether to perform the cyclic refresh operation of the CAS before
RAS (CBR) type. When starting the cyclic refresh, regardless of areas 4 and 5, set the
REFE bit of DMCR4 or DMCR5 to "1" and set the STR bit of the refresh control register
(RFCF).
0: Does not perform a cyclic refresh (initial value).
1: Performs cyclic refresh with an interval specified by t he refresh control register (RFCR).
[bit 3] PAR (PARity select bit)
This device supports no parity function.
Setting this bit has no effect.
[bit 2] PERR (Parity ERRor bit)
This device supports no parity function.
Setting this bit has no effect.
[bit 1] PEIE (Parity Error Interrupt Enable bit)
The PEIE bit specifies whether to output an interrupt request fo r a parity error.
This device supports no parity function.
Be sure to set this bit to "0".
Bus Width Combinations
Table 4.10.2 lists the combinations of bus widths availab le in areas 4 and 5.
Table 4.10-2 Combinations of Bus Widths Available in Areas 4 and 5
Combination Area 4 Area 5
1 Usual: 16/8 bits Usual: 16/8 bits
2 Usual: 16/8 bits DRAM: 16 bits (C/W = 0, 1)
3 Usual: 16/8 bits DRAM: 8 bits (C/W = 0, 1)
4 DRAM: 16 bits (C/W = 0, 1) Usual: 16/8 bits
5 DRAM: 16 bits (C/W = 0, 1) DRAM: 16 bits (C/W = 0, 1)
6 DRAM: 16 bits (C/W = 0, 1) DRAM: 8 bits (C/W = 0, 1)
7 DRAM: 8 bits (C/W = 0, 1) Usual: 16/8 bits
8 DRAM: 8 bits (C/W = 0, 1) DRAM: 16 bits (C/W = 0, 1)
9 DRAM: 8 bits (C/W = 0, 1) DRAM: 8 bits (C/W = 0, 1)