Product specifications
ProSavageDDR P4M266 – VT8751 P4 DDR SMA North Bridge
Revision 1.1, July 19, 2002 -15- Pin Descriptions
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Technologies, Inc.
V-Link Interface
Signal Name Pin # I/O Signal Description
VAD7,
VAD6 /strap,
VAD5 /strap,
VAD4 /strap,
VAD3 /strap,
VAD2 /strap,
VAD1 /strap,
VAD0 /strap
AB2
AB1
W2
AA5
W1
AB3
W3
W5
IO
IO
IO
IO
IO
IO
IO
IO
Address / Data Bus. SB
Strap
Strap Name Definition (L=strap low, H=high) Register Pin
VAD6 Auto-Configure L=Disable (use on-chip defaults) Rx54[5] SDA2
H=Enable (get from ROMSIP)
VAD5 AGTL+ Drive Strength 4x L=1x, H=4x SDA1
VAD4 AGTL+ Drive Strength 2x L=1x, H=2x SDA0
VAD3 AGTL+ Internal Pullups L=Disable, H=Enable. Rx50[6] SA19
VAD2 In Order Queue Depth L=1-level, H=8-level. Rx50[7] SA18
VAD1 CPU Clock Speed Msb LL=66, LH=100, Rx54[7] SA17
VAD0 CPU Clock Speed Lsb HL=Auto, HH=133 MHz Rx54[6] SA16
VBE#
V5 IO
Byte Enable.
UPCMD
Y1 I
Command from Client-to-Host.
UPSTB
AA4 I
Strobe from Client-to-Host.
UPSTB#
Y3 I
Complement Strobe from Client-to-Host.
DNCMD
AA2 O
Command from Host-to-Client.
DNSTB
AA1 O
Strobe from Host-to-Client.
DNSTB#
AA3 O
Complement Strobe from Host-to-Client.
CRT Interface
Signal Name Pin # I/O Signal Description
AR
B6 AO Analog Red. Analog red output to the CRT monitor.
AB
B5 AO Analog Blue. Analog blue output to the CRT monitor.
AG
A5 AO Analog Green. Analog green output to the CRT monitor.
HSYNC
B8 O Horizontal Sync. Output to CRT.
VSYNC
A8 O Vertical Sync. Output to CRT.
RSET
A6 AI Reference Resistor. Tie to GNDRGB through an external 140Ω resistor to control the
RAMDAC full-scale current value.
SMB / I2C Interface
Signal Name Pin # I/O Signal Description
SPCLK[2:1]
E9, C9 IO Serial Port (SMB/I2C) Clocks. These are the clocks for serial data transfer. SPCLK1 is
typically used for I
2
C communications. As an output, it is programmed via CRA0[0]. As an
input, its status is read via CRA0[2]. In either case the serial port must be enabled by
CRA0[4] = 1. SPCLK2 is typically used for DDC monitor communications. As an output, it
is programmed via CRB1[0]. As an input, its status is read via CRB1[2]. The port is enabled
via CRB1[4] = 1.
SPDAT[2:1]
E8, D9 IO Serial Port (SMB/I2C) Data. These are the data signals used for serial data transfer.
SPDAT1 is typically used for I
2
C communications. As an output, it is programmed via
CRA0[1]. As an input, its status is read via CRA0[3]. In either case the serial port must be
enabled by CRA0[4] = 1. SPDAT2 is typically used for DDC monitor communications. As
an output, it is programmed via CRB1[1]. As an input, its status is read via CRB1[3]. The
port is enabled via CRB1[4] = 1.