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3.6
Intel
3.6.1
SDRAM Connections
Table 3-6. SDRAM Connectivity
82443GX Pins/Connection
CKBF buffer outputs DCLK[x:y]
CS_A[7:0]#
CS_B[7:0]#
GND
MAx[9:0]#, MAx10
MAx11#
Max12#
MAA13#, MAB13
MAA14, MAB14
MDx[63:0] (from FET)
MD[63:0] (NO FET)
MECC[7:0]
Strap for SMBus individual
Address
SMBDATA
SMBCLK
SCASx#
SRASx#
WEx#
NOTES:
1. Some of the pin ranges above are dependent on which DIMM is being reviewed. "x" and "y" indicate signal
copies.
2. MAAxx address lines need to be routed to the two DIMM sockets closest to the 82443GX. MABxx# will be
routed to the one or two DIMM sockets furthest from the 82443GX. Selected MABxx# lines will also require
strapping options to properly configure the 82443GX.
3. Can either be a FET or no-FET solution. A FET solution will require the use of six 56-pin FET switch
multiplexers. The most common FET switches available are of the 5V family. A no-FET solution must adhere
to the strict no-FET design layout guidelines.
4. The MD, MECC and the DQM lines require "T" routing for load balancing.
5. Copies of SRAS#, SCAS#, WE# should be evenly distributed throughout the memory array.
6. MABxx# pins (except for MAB10, MAB13, and MAB14) are inverted for signal integrity reasons. MAB10,
MAB13, and MAB14 are not inverted to maintain correct SDRAM commands.
7. Series termination resistors are not required on the motherboard for DIMM signals (MD, MA, DQM, CS, etc.).
8. See the SDRAM Serial Presence Detect Data Structure specification for information on the EEPROM register
contents.
9. The PC SDRAM Unbuffered DIMM Specification, Rev 1.0, dated Feb 1998 , shows pin 81 of the DIMM
module is the WP (write protect) pin for the SPD EEPROM. The block diagrams show there is a 47K pull-
down resistor tied to the WP pin. This allows the DIMM manufacturers to write SPD data to the EEPROM. An
OEM may wish to use the SPD EEPROM to write information into the DIMMs at production for system level
checkout to identify the DIMM installed as being shipped with the system. For this reason, the OEM may wish
to include some logic to control the level on pin 81 of the DIMM modules so that after the DIMM is tagged,
they can be write protected again. If this pin is pulled high on the motherboard, the DIMM SPD EEPROM is
write protected. Pin 81 of the DIMM sockets on the 82443GX dual processor reference schematics currently
shows a "NC", no connects. If an OEM wishes to write protect the SDRAM SPD EEPROMS, then these pins
should be pulled high.
®
Intel
440GX AGPset Design Guide
440GX AGPset Memory Interface
CK[3:0] (4 DCLKs per DIMM)
S#[1:0] (2 CS per DIMM)
S#[3:2] (2 CS per DIMM)
A13
A[10:0]
BA0
BA1
A11
A12
DQ[63:0]
CB[7:0]
SA[2:0]
SDA
SCL
CAS#
RAS#
WE0#
DIMM Pins
Clock
Chip Select
Chip Select
Address
Address
Address
Address
Address
Address
Data
Error Checking and Correction
SMBus Address
SMBus Data
SMBus Clock
SDRAM Column Address Select
SDRAM Row Address Select
Write Enable
Design Checklist
Pin Function
3-14
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