Intel manual Intel 440GX AGPset Memory Interface, Sdram Connections, Sdram Connectivity

Design Checklist

3.6Intel® 440GX AGPset Memory Interface

3.6.1SDRAM Connections

Table 3-6. SDRAM Connectivity

82443GX Pins/Connection	DIMM Pins	Pin Function
CKBF buffer outputs DCLK[x:y]	CK[3:0] (4 DCLKs per DIMM)	Clock
CS_A[7:0]#	S#[1:0] (2 CS per DIMM)	Chip Select
CS_B[7:0]#	S#[3:2] (2 CS per DIMM)	Chip Select
GND	A13	Address
MAx[9:0]#, MAx10	A[10:0]	Address
MAx11#	BA0	Address
Max12#	BA1	Address
MAA13#, MAB13	A11	Address
MAA14, MAB14	A12	Address
MDx[63:0] (from FET)	DQ[63:0]	Data
MD[63:0] (NO FET)
MECC[7:0]	CB[7:0]	Error Checking and Correction
Strap for SMBus individual	SA[2:0]	SMBus Address
Address
SMBDATA	SDA	SMBus Data
SMBCLK	SCL	SMBus Clock
SCASx#	CAS#	SDRAM Column Address Select
SRASx#	RAS#	SDRAM Row Address Select
WEx#	WE0#	Write Enable

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 3-14