Accelerated Graphics Port Interface Specification

AGP3.0 Interface Specification

Rev. 1.0

3.5.6 Motherboard / Add-in Card Interoperability

Interoperability is required by AGP3.0 implementations. A box with a ü symbol means the configuration

is legal while a grayed out box indicates an illegal configuration and must be excluded either by electrical

or mechanical means. Table 35 shows the matrix of compatible motherboard and add-in cards and their

operating and signaling voltage.

Table 35: Motherboard / Add-in Card Interoperability

AGP2.0 Cards AGP3.0 Cards

Motherboard 3.3 1.5 Universal Universal

1.5V

AGP3.0

AGP3.0 Universal

AGP3.0

AGP 3.3 ü (3.3V) ü (3.3V) ü (3.3V)

AGP 1.5 ü (1.5V) ü (1.5V) ü (1.5V) (1) ü (1.5V)

AGP Universal ü (3.3V) ü (1.5V) ü (1.5V) ü (1.5V) (1) ü (1.5V)

Universal 1.5V AGP3.0 ü (1.5V) ü (1.5V) ü (0.8V) ü (0.8V) ü (0.8V)

AGP3.0 (2) (2) ü (0.8V) ü (0.8V) ü (0.8V)

Universal AGP3.0 ü (3.3V) ü (1.5V) ü (1.5V) ü (0.8V) ü (0.8V) ü (0.8V)

Indicates that this combination is precluded by position of key in AGP connector

/ NOTES

1 AGP3.0 cards can physically plug into an AGP 1.5V or universal connector

but will not function. In these configurations, the mechanical keying on the

AGP motherboard connector does not prevent the AGP3.0 graphics card

from physically plugging into the motherboard. Since the AGP2.0

motherboard will not look at GC_DET# to identify an AGP3.0 card, it is the

responsibility of the AGP3.0 Card to use the newly defined MB_DET# pin to

detect the non-AGP3.0 motherboard and prevent improper functioning or

damage. The Card must be capable of tolerating 1.5V signals from the

AGP motherboard. AGP3.0 cards will also need to strap TYPEDET# to

indicate 1.5V, otherwise an AGP Universal motherboard may drive 3.3V to

the card. Since the AGP3.0 card does not support the signaling mode of

the motherboard component, it must not attempt to respond to any cycle

(e.g. PCI configuration cycle).

2 AGP cards can plug into an AGP3.0-only motherboard but will not be

powered and will not function. In these configurations, the mechanical

keying on the AGP3.0 motherboard connector does not prevent the

AGP2.0 graphics card from plugging into the motherboard. However, the

AGP3.0 motherboard will be able to detect the presence of a non-AGP3.0

Card using a newly added signal pin GC_DET# and use this information to

prevent the configuration from functioning improperly. The motherboard

must detect that GC_DET# is not asserted and remove power from V

DDQ

pins.

Interoperability requires that the AGP3.0 devices and boards have a superset of the electrical

characteristics of all the signaling levels and transfer rates they support. This includes I/O timings,