Intel 740, Design Manual

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Revision 0.91
19
SO-DIMM Module — Unbuffered SDRAM/SGRAM Graphics
8.3 Data Routing
Data lodading is two loads per line, maximum. Routing should be performed using a T-topology, as
shown below.
Byte-ordering (along with the respective Data Mask, DQM) within the SDRAM/SGRAM should
be swapped to optimize routing.
The following table lists the allowable stub lengths for the data line routing.
Figure 11.Data Routing
A010.vsd
a
o
Bank 0
d
c
A B
S
C D
b
o
Bank 1
Table 8. Byte Ordering
Module Byte Front-Side Memory Byte Back-Side Memory Byte n value
BYTE 0 Memory B; BYTE 0 Memory D; BYTE 3
n
= 115 pS
BYTE 1 Memory B; BYTE 3 Memory D; BYTE 0 n = 35 pS
BYTE 2 Memory B; BYTE 1 Memory D; BYTE 2
n
= 35 pS
BYTE 3 Memory B; BYTE 2 Memory D; BYTE 1 n = 115 pS
BYTE 4 Memory A; BYTE 1 Memory C; BYTE 2
n
= 115 pS
BYTE 5 Memory A; BYTE 2 Memory C; BYTE 1 n = 35 pS
BYTE 6 Memory A; BYTE 0 Memory C; BYTE 3
n
= 35 pS
BYTE 7 Memory A; BYTE 3 Memory C; BYTE 0 n = 115 pS