
3-46
MPC106 PCIB/MC User's Manual
MOTOROLA
See Figure 3-33 and Table 3-33 for memory control configuration register 3 (MCCR3) bit
settings.
Figure 3-33. Memory Control Configuration Register 3 (MCCR3)—0xF8
15–2
REFINT
All 0s
Refresh interval. These bits directly represent the number of clock
cycles between CBR refresh cycles. One row is refreshed in each
RAM bank during each CBR refresh cycle. The value for REFINT
depends on the specific RAMs used and the operating frequency
of the MPC106. See Section 6.3.10, “DRAM/EDO Refresh,” or
Section 6.4.9, “SDRAM Refresh,” for more information. Note that
the period of the refresh interval must be greater than the
read/write access time to insure that read/write operations
complete successfully.
1
BUF_MODE
1
Buffer mode. This bit controls how BCTL0 and BCTL1 operate.
See Section 6.2, “Memory Interface Signal Buffering,” for more
information.
0
BCTL0 enables the buffer for write operations; BCTL1
enables the buffer for read operations.
1
BCTL0 controls the buffer direction (W/R); BCTL1 acts as
buffer enable.
0
RMW_PAR
0
Read-modify-write (RMW) parity enable. This bit controls how the
MPC106 writes parity bits to DRAM/EDO/SDRAM. Note that this
bit does not enable parity checking and generation. PCKEN must
be set to enable parity checking. Also note that this bit and
ECC_EN cannot both be set to 1. See Section 6.3.8, “DRAM/EDO
Parity and RMW Parity,” or Section 6.4.8, “SDRAM Parity and
RMW Parity,” for more information.
0
RMW parity disabled
1
RMW parity enabled
Table 3-32. Bit Settings for MCCR2—0xF4 (Continued)
Bit
Name
Reset
Value
Description
31
28 27
24 23
20 19 18
15 14
12 11
9
8
6
5
3
2
0
CPX
Reserved
BSTOPRE_U
REFREC
RDLAT
RAS
6P
CAS
5
CP
4
CAS
3
RCD
2
RP
1