TITLE
    Composite Sync on Green: Which Apple Computers Have It? (9/95)
Article ID:
Created:
Modified: 		13798
10/28/93
9/13/95
TOPIC



    Could you provide information about which Apple computers have a Composite Sync on Green and which models do not? This function is helpful when connecting third party monitors to Macintosh computers.

DISCUSSION


    Sync on green refers to the practice of sending the video synchronization signal along with the green color signal. Previously released Macintosh models with built-in video have supported sync on green.

    For computers without sync on green, a third party adapter is necessary if you wish to connect a third party monitor which requires sync on green.

    No Sync On Green
    ----------------
    LC III
    LC 475
    LC 575
    LC 550
    Performa 550/560/575/577/578
    Performa 460/466/467
    Performa 475/476
    Quadra 605
    Quadra 840AV
    Quadra 660AV
    Macintosh 630 family
    All portable computers (also no blanking)
    Duo Dock (also no blanking)
    Duo Dock II (programmable *)
    All Power Macintosh models


    Sync On Green
    -------------
    Quadra 700 (programmable *)
    Quadra 800
    Quadra 900 (programmable *)
    Quadra 950 (programmable *)
    Centris 610
    Centris 650
    Quadra 610
    Quadra 650


    Note:
    * - The programmable feature refers to the fact that the computer
    automatically disables the sync on green signal whenever the sense lines detect that a VGA monitor is connected.


    Questions and Answers
    =====================

    Question:
    Why is Sync on Green not supported on all computers?

    Answer:
    1) Many users have had problems with sync on green when hooking up third- party monitors; mainly multi-frequency displays from the PC world. Since these displays are increasingly being used with Macintosh, the lack of sync on green increases the number and compatibility of displays available.

    2) The current popular video standards, VGA and VESA, dictate using separate sync signals, not sync on the green video.

    3) No current Apple monitors support sync on green.

    4) The new monitors with power-saving modes (monitors which can be put to sleep, thus consuming less energy) typically use the separate sync lines to signal the monitor to enter a low power state. Since separate sync lines run to the monitor anyway, sync on green does not make sense.

    5) The ability to strip sync off the green video adds cost and complexity to a monitor.


    Question:
    My monitor will not work without sync on green, how can I get

    Unfortunately, there is very little you can do about this problem. This seems to affect only one or two major Macintosh display manufacturers, and affects only some of their displays.

    The cable or adapter doesn't pass separate sync lines to the monitor
    --------------------------------------------------------------------
    This is easily fixed by replacing/altering the cable or adapter. Companies such as Griffin Communications provide adapters to provide the sync on green capability.

    PLEASE NOTE: One of the main reasons cables and adapters don't pass through the separate sync lines is because sync on green is there in the first place. Since the sync signal on green video causes some monitors to display a greenish tint when they see (and therefore use) the separate sync signals, simply not passing the separate sync signals to the monitor cures the problem. This workaround will fix the problem on a majority of the monitors available.


    Article Change History:
    13 Sep 1995 - Combined several articles.
    22 Mar 1995 - Corrected wording of Duo Dock.
    09 Mar 1995 - Additional Macintosh models documented.

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Document Information
Product Area: Monitors-Displays
Category: General Topics
Sub Category: General Topics

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