Specifications

CHAPTER 1

Overview of the AppleVision 1710AV and 1710 Displays

16 New Display Connections Speciﬁcations

the new Display Manager. This also allows the Macintosh to display stable on-screen

video early in the boot process. There is also another reason for using this sense code, as

described in “Designing Display Data Channel (DDC) Displays” on page 16.

Because the AppleVision 1710 displays, and other future displays from third parties, will

rely on this new strategy, all PCI cards as well as Nubus cards intended to support these

multiple-scan displays must follow the guidelines outlined in Designing PCI Cards and

Drivers for Power Macintosh Computers. These changes in the Display Manager work with

PCI drivers on all Power Macintosh computers and with Nubus drivers on all

color-capable Macintosh computers running System 7.5.

Designing Smart Displays 1

If you are designing a smart display, that is a display where the Macintosh computer can

control some functions of the display via the ADB cable, serial port, or other

communications method, the display should include as one of its functions the

capability of independently “wiggling” or toggling the value of the sense lines. This is

done by means of a call to the display’s Port Component wiggle selectors, so that the

Display Manager can establish the connection between the Port Component and the

gDevice associated with the display. (Refer to the AV Architecture Developer Note for more

information.) If the display cannot implement wiggling, the Sound & Displays control

panel will show two display ports (one for the graphics device, one for the display)

rather than one combined port, and it will be up to the developer to determine which

gDevice is used by the display, if this information is needed.

Note

In some Apple publications, the term “tagging” is used instead of the

term “wiggling.” ◆

Designing Display Data Channel (DDC) Displays 1

The AppleVision 1710 display is the ﬁrst Apple display that provides compatibility with

Windows 95 Plug-and-Play via the Display Data Channel (DDC) standard. This standard

allows host systems to get information from the monitor, and to conﬁgure the

information correctly for the display adapter being used. DDC is expected to become

increasingly important in the Macintosh world, and may eventually replace the ADB

port and the serial port as the preferred methods of communicating with smart displays.

For compatibility with future Macintosh graphics devices, you should follow the

standard set by the AppleVision 1710 displays when you are designing displays.

Speciﬁcally, the AppleVision 1710 displays implement both DDC1 and DDC2B standards

through a scheme that maintains compatibility with the Macintosh sense-code-detection

mechanism.

In AppleVision 1710 displays, a 24LC21 serial EEPROM is used to implement DDC, and

sense line 1 (pin 10) on the video cable is used for serial data (SDA), while sense line 2

(pin 7) on the video cable is used for the serial clock (SCL).