
E
2.1.12.
82371AB (PIIX4)
39
4/9/97 2:23 PM PIIX4aDS
INTEL CONFIDENTIAL
(until publication date)
PRELIMINARY
OTHER SYSTEM AND TEST SIGNALS
Name
Type
Description
CONFIG1
I
CONFIGURATION SELECT 1.
This input signal is used to select the type of
microprocessor being used in the system. If CONFIG1=0, the system contains a
Pentium microprocessor. If CONFIG1=1, the system contains a Pentium II
microprocessor. It is used to control the polarity of INIT and CPURST signals.
CONFIG2
I
CONFIGURATION SELECT 2.
This input signal is used to select the positive or
subtractive decode of FFFF0000h–FFFFFFFFh memory address range (top 64 Kbytes).
If CONFIG[2]=0, the PIIX4 will positively decode this range. If CONFIG[2]=1, the PIIX4
will decode this range with subtractive decode timings only. The input value of this pin
must be static and may not dynamically change during system operations.
PWROK
I
POWER OK.
When asserted, PWROK is an indication to PIIX4 that power and PCICLK
have been stable for at least 1 ms. PWROK can be driven asynchronously. When
PWROK is negated, PIIX4 asserts CPURST, PCIRST# and RSTDRV. When PWROK is
driven active (high), PIIX4 negates CPURST, PCIRST#, and RSTDRV.
SPKR
O
SPEAKER.
The SPKR signal is the output of counter timer 2 and is internally “ANDed”
with Port 061h bit 1 to provide the Speaker Data Enable. This signal drives an external
speaker driver device, which in turn drives the ISA system speaker.
During Reset:
Low
After Reset:
Low
During POS:
Last State
TEST#
I
TEST MODE SELECT.
The test signal is used to select various test modes of PIIX4.
This signal must be pulled up to V
CC
(SUS) for normal operation.
2.1.13.
POWER AND GROUND PINS
Name
Type
Description
V
CC
V
CORE VOLTAGE SUPPLY.
These pins are the primary voltage supply for the PIIX4
core and IO periphery and must be tied to 3.3V.
V
CC
(RTC)
V
RTC WELL VOLTAGE SUPPLY.
This pin is the supply voltage for the RTC logic and
must be tied to 3.3V.
V
CC
(SUS)
V
SUSPEND WELL VOLTAGE SUPPLY.
These pins are the primary voltage supply for
the PIIX4 suspend logic and IO signals and must be tied to 3.3V.
V
CC
(USB)
V
USB VOLTAGE SUPPLY.
This pin is the supply voltage for the USB input/output
buffers and must be tied to 3.3V.
V
REF
V
VOLTAGE REFERENCE.
This pin is used to provide a 5V reference voltage for 5V safe
input buffers.
V
REF
must be tied to 5V in a system requiring 5V tolerance. In a 5V tolerant system, this
signal must power up before or simultaneous to V
CC
. It must power down after or
simultaneous to V
CC
.
In a non-5V tolerant system (3.3V only), this signal can be tied directly to V
CC
. There are
then no sequencing requirements.
V
SS
V
CORE GROUND.
These pins are the primary ground for PIIX4.
V
SS
(USB)
V
USB GROUND.
This pin is the ground for the USB input/output buffers.