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AMD Geode SC1201 User Manual

Page 20

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20

AMD Geode™ SC1200/SC1201 Processor Data Book

Architecture Overview

32579B

GX_BASE+8408h-840Bh

MC_BANK_CFG (R/W)

Reset Value: 41104110h

31:16

RSVD (Reserved). Write as 0070h

15

RSVD (Reserved). Write as 0.

14

SODIMM_MOD_BNK (SODIMM Module Banks - Banks 0 and 1). Selects number of module banks installed per SODIMM
for SODIMM:

0: 1 Module bank (Bank 0 only)
1: 2 Module banks (Bank 0 and 1)

13

RSVD (Reserved). Write as 0.

12

SODIMM_COMP_BNK (SODIMM Component Banks - Banks 0 and 1). Selects the number of component banks per
module bank for SODIMM:

0: 2 Component banks
1: 4 Component banks

Banks 0 and 1 must have the same number of component banks.

11

RSVD (Reserved). Write as 0.

10:8

SODIMM_SZ (SODIMM Size - Banks 0 and 1). Selects the size of SODIMM:

000: 4 MB

010: 16 MB

100: 64 MB

110: 256 MB

001: 8 MB

011: 32 MB

101: 128 MB

111: 512 MB

This size is the total of both banks 0 and 1. Also, banks 0 and 1 must be the same size.

7

RSVD (Reserved). Write as 0.

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

31

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

19

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

15

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

Table 2-2. SC1200/SC1201 Processor Memory Controller Registers (Continued)

Bit

Description

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