Apple Display Connector

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Apple Display Connector
AppleDisplayConnector.jpg
ADC cable end
Type analog/digital video connector + USB
Designer Apple Computer
Manufacturer Apple Computer
Superseded by DVI (June 2004)
Hot pluggable Yes
External Yes
Pins 35
Max. voltage 25 V
Max. current 4.0 A
Pin 1 25 V Supply
Pin 2 25 V Supply
Pin 3 LED
Pin 4 TMDS Data0–
Pin 5 TMDS Data0+
Pin 6 TMDS Data0/5 Shield
Pin 7 TMDS Data5–
Pin 8 TMDS Data5+
Pin 9 DDC Data
Pin 10 Vsync
Pin 11 25 V Return
Pin 12 25 V Return
Pin 13 Soft Power
Pin 14 TMDS Data1–
Pin 15 TMDS Data1+
Pin 16 TMDS Data1/3 Shield
Pin 17 TMDS Data3–
Pin 18 TMDS Data3+
Pin 19 DDC CLock
Pin 20 Clock Return
Pin 21 USB Data+
Pin 22 USB Data–
Pin 23 USB Return
Pin 24 TMDS Data2–
Pin 25 TMDS Data2+
Pin 26 TMDS Data2/4 Shield
Pin 27 TMDS Data4–
Pin 28 TMDS Data4+
Pin 29 Clock+
Pin 30 Clock-
C1 Analog Blue Video
C2 Analog Green Video
C3 Analog Horizontal Sync
C4 Analog Red Video
C5 Analog RGB Return and DDC Return

The Apple Display Connector (ADC) is a proprietary modification of the DVI connector that combines analog and digital video signals, USB, and power all in one cable. Apple used ADC for its LCD-based Apple Cinema Displays and their final CRT displays, before deciding to use standard DVI connectors on later models.

First implemented in the July 2000 Power Mac G4 and G4 Cube, ADC disappeared from displays in June 2004 when Apple introduced the aluminum-clad 20", 23", and 30" Apple Cinema Displays, which feature separate DVI, USB and FireWire connectors, and their own power supplies. The ADC was still standard on the Power Mac G5 until April 2005, when new models meant the only remaining Apple product with an ADC interface was the single processor Power Mac G5 introduced in October 2004. This single processor Power Mac G5 was discontinued soon after in June 2005.

Compatibility[edit]

The Apple Display Connector, debuted in the Apple Studio Display, is physically incompatible with a standard DVI connector, as was previously used in the PowerBook G4 and the older Power Mac G4. The Apple DVI to ADC Adapter,[1] which cost $149US at launch but was in 2002 available for $99US,[2] takes USB and DVI connections from the computer, together with power, and combines them into an ADC connection, allowing ADC monitors to be used with DVI-based machines.

The initial implementation of ADC on some models of Power Mac G4s involved the removal of DVI connectors from these computers. This change necessitated a passive ADC to DVI adapter to use a DVI monitor.

The ADC carries up to 100 W of power, an insufficient amount to run most 19-inch or bigger CRTs widely available during ADC's debut, nor can it run contemporary flat panels marketed for home entertainment (many of which support DVI or VGA connections) without an adapter. The power limit was an important factor for Apple to abandon ADC when it launched the 30-inch Apple Cinema HD Display.

On newer DVI-based displays lacking ADC, Apple still opted for a single "ganged cable" that connects the separate signal cables to each other so they cannot tangle. Such cables, however, employ standard DVI, power, USB and FireWire connectors, avoiding drawbacks to ADC. Beginning in 2008, Apple began transitioning away from DVI, adopting the increasingly common DisplayPort signalling standard, and developed their own Mini DisplayPort connector beginning with the first LED-backlit Cinema Displays. As of 2013, Apple no longer uses a DVI-based interface for any of its displays.

Apple no longer supports ADC adapters, or monitors.

Pin 3 and 11[edit]

Power is supplied to the ADC port by an additional finger connector on the video card, which plugs into a slot on the motherboard between the AGP slot and the back panel of the computer; on G4 Macs, some power is also sent through AGP pins 3 and 11. When ADC was introduced, AGP pins 3 and 11 were unassigned. In AGP 8x, pins 3 and 11 were assigned, so because of that, G4s are not directly compatible with AGP 8x. G5 Macs draw all power from the finger connector and therefore are 8x compatible. To use an AGP 8x card in a G4, pins 3 and 11 must be somehow disabled; this can be done by placing tape over the conductive part of the pin, slicing the PCB traces, or on some cards, desoldering surface mount resistors.

See also[edit]

References[edit]

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