User Guide

166
F
F
o
o
r
r
t
t
r
r
e
e
s
s
s
s
9
9
1
1
0
0
0
0
O
O
n
n
l
l
i
i
n
n
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e
M
M
a
a
n
n
u
u
a
a
l
l
Open
A
S
S
M
M
B
B
u
u
s
s
(
(
S
S
y
y
s
s
t
t
e
e
m
m
M
M
a
a
n
n
a
a
g
g
e
e
m
m
e
e
n
n
t
t
B
B
u
u
s
s
)
)
SMBus is also called I2C bus. It is a two-wire bus developed for component communication
(especially for semiconductor IC). For example, set clock of clock generator for jumper-less
motherboard. The data transfer rate of SMBus is only 100Kbit/s, it allows one host to communicate
with CPU and many masters and slaves to send/receive message.
S
S
P
P
D
D
(
(
S
S
e
e
r
r
i
i
a
a
l
l
P
P
r
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s
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n
n
c
c
e
e
D
D
e
e
t
t
e
e
c
c
t
t
)
)
SPD is a small ROM or EEPROM device resided on the DIMM or RIMM. SPD stores memory
module information such as DRAM timing and chip parameters. SPD can be used by BIOS
to
decide best timing for this DIMM or RIMM.
U
U
l
l
t
t
r
r
a
a
D
D
M
M
A
A
/
/
3
3
3
3
Unlike traditional PIO/DMA mode, which only uses the rising edge of IDE command signal to
transfer data. UDMA/33 uses both rising edge and falling edge, the data transfer rate is double of
the PIO mode 4 or DMA mode 2.
16.6MB/s x2 = 33MB/s