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Signal Description
D15343-003 27
3.0 Signal Description
This section describes the Intel
®
82854 GMCH signals. These signals are arranged in functional
groups according to their associated interface. The following notations are used to describe the
signal type.
The signal description also includes the type of buffer used for the particular signal:
Note: System Address and Data Bus signals are logically inverted signals. In other words, the actual
values are inverted from what appears on the system bus. This must be taken into account and the
addresses and data bus signals must be inverted inside the GMCH. All processor control signals
follow normal convention: A 0 indicates an active level (low voltage), and a 1 indicates an active
level (high voltage).
Notation Description
I Input pin
O Output pin
I/O Bi-directional Input/Output pin
Buffer Description
AGTL+ Open Drain AGTL+ interface signal. Refer to the AGTL+ I/O
Specification for complete details. The GMCH integrates AGTL+
termination resistors, and supports VTTLF of 1.05 V ± 5%. AGTL+
signals are "inverted bus" style where a low voltage represents a
logical 1.
DVO DVO buffers (1.5-V tolerant)
Hub Compatible to Hub interface 1.5
SSTL_2 Stub Series Termination Logic compatible signals (2.5-V tolerant)
LVTTL Low Voltage TTL compatible signals (3.3-V tolerant)
CMOS CMOS buffers (3.3-V tolerant)
Analog Analog signal interface
Ref Voltage reference signal