SC2200 datasheet(14/433 Pages) NSC

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Architecture Overview (Continued)

6:4

SODIMM_PG_SZ (SODIMM Page Size - Banks 0 and 1). Selects the page size of SODIMM:

000: 1 KB

010: 4 KB

1xx: 16 KB

001: 2 KB

011: 8 KB

111: SODIMM not installed

Both banks 0 and 1 must have the same page size.

3:0

RSVD (Reserved). Write as 0.

GX_BASE+840Ch-840Fh

MC_SYNC_TIM1 (R/W)

Reset Value: 2A733225h

RSVD (Reserved). Write as 0.

30:28

LTMODE (CAS Latency). CAS latency is the delay, in SDRAM clock cycles, between the registration of a read command

and the availability of the first piece of output data. This parameter significantly affects system performance. Optimal setting

should be used. If an SODIMM is used, BIOS can interrogate EEPROM across the ACCESS.bus interface to determine this

value:

000: Reserved

010: 2 CLK

100: 4 CLK

110: 6 CLK

001: Reserved

011: 3 CLK

101: 5 CLK

111: 7 CLK

This field will not take effect until SDRAMPRG (bit 0 of MC_MEM_CNTRL1) transitions from 0 to 1.

27:24

RC (RFSH to RFSH/ACT Command Period, tRC). Minimum number of SDRAM clock between RFSH and RFSH/ACT

commands:

0000: Reserved

0100: 5 CLK

1000: 9 CLK

1100: 13 CLK

0001: 2 CLK

0101: 6 CLK

1001: 10 CLK

1101: 14 CLK

0010: 3 CLK

0110: 7 CLK

1010: 11 CLK

1110: 15 CLK

0011: 4 CLK

0111: 8 CLK

1011: 12 CLK

1111: 16 CLK

23:20

RAS (ACT to PRE Command Period, tRAS). Minimum number of SDRAM clocks between ACT and PRE commands:

0000: Reserved

0100: 5 CLK

1000: 9 CLK

1100: 13 CLK

0001: 2 CLK

0101: 6 CLK

1001: 10 CLK

1101: 14 CLK

0010: 3 CLK

0110: 7 CLK

1010: 11 CLK

1110: 15 CLK

0011: 4 CLK

0111: 8 CLK

1011: 12 CLK

1111: 16 CLK

RSVD (Reserved). Write as 0.

18:16

RP (PRE to ACT Command Period, tRP). Minimum number of SDRAM clocks between PRE and ACT commands:

000: Reserved

010: 2 CLK

100: 4 CLK

110: 6 CLK

001: 1 CLK

011: 3 CLK

101: 5 CLK

111: 7 CLK

RSVD (Reserved). Write as 0.

14:12

RCD (Delay Time ACT to READ/WRT Command, tRCD). Minimum number of SDRAM clock between ACT and

READ/WRT commands. This parameter significantly affects system performance. Optimal setting should be used:

000: Reserved

010: 2 CLK

100: 4 CLK

110: 6 CLK

001: 1 CLK

011: 3 CLK

101: 5 CLK

111: 7 CLK

RSVD (Reserved). Write as 0.

10:8

RRD (ACT(0) to ACT(1) Command Period, tRRD). Minimum number of SDRAM clocks between ACT and ACT command

to two different component banks within the same module bank. The memory controller does not perform back-to-back Acti-

vate commands to two different component banks without a READ or WRITE command between them. Hence, this field

should be written as 001.

RSVD (Reserved). Write as 0.

6:4

DPL(Data-intoPRE command period, tDPL). Minimum number of SDRAM clocks from the time the last write datum is

sampled till the bank is precharged:

000: Reserved

010: 2 CLK

100: 4 CLK

110: 6 CLK

001: 1 CLK

011: 3 CLK

101: 5 CLK

111: 7 CLK

3:0

RSVD (Reserved). Leave unchanged. Always returns a 101h.

Note:

Refer to the SDRAM manufacturer’s specification for more information on component banks.

Table 1-2. SC2200 Memory Controller Registers (Continued)

Bit

Description

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