Signal Description

R

2.5Clocks, Reset, and Miscellaneous Signals

Signal Name

Type

Description

 

 

 

BCLK

I

Differential Host Clock In: These pins receive a differential host clock

BCLK#

CMOS

from the external clock synthesizer. This clock is used by all of the MCH

 

logic that is in the host clock domain.

 

 

 

 

 

66IN

I

66 MHz Clock In: This pin receives a 66 MHz clock from the clock

 

CMOS

synthesizer. This clock is used by AGP/PCI and hub interface clock

 

 

domains.

 

 

Note: That this clock input is 3.3 V tolerant.

 

 

 

SCK[11:0]

O

System Memory Clocks (SDR): These signals deliver a synchronized

 

CMOS

clock to the DIMMs. There are two per row.

 

 

 

RSTIN#

I

Reset In: When asserted, this signal asynchronously resets the MCH

 

CMOS

logic. RSTIN# is connected to the PCIRST# output of the ICH2. All

 

 

AGP/PCI output and bi-directional signals will also three-state compliant

 

 

to PCI Rev 2.0 and 2.1 specifications.

 

 

Note: This input needs to be 3.3 V tolerant.

 

 

 

TESTIN#

I

Test Input: This pin is used for manufacturing and board level test

 

CMOS

purposes.

 

 

Note: This signal has an internal pull-up resistor.

 

 

 

28

Intel® 82845 MCH for SDR Datasheet

Page 28
Image 28
Intel 845 manual Clocks, Reset, and Miscellaneous Signals, Bclk, BCLK# Cmos, Rstin#, Testin#