TITLE
    Performa 600: Internal Video Support
Article ID:
Created:
Modified: 		10677
9/10/92
9/10/92
TOPIC

    Performa 600: Internal Video Display Support



    This article describes the Macintosh Performa 600's internal video display
    support.

DISCUSSION


    The following chart lists the monitors supported by Performa 600's internal
    video:

    MON ID Monitor Cols/ Vertical Horizontal
    3 2 1 Selected Rows Refresh Refresh Bandwidth
    -----------------------------------------------------------------
    0 0 1 reserved

    0 1 0 12" RGB 512 x 384 60.15 Hz 24.48 KHz 15.6672 MHz

    1 1 0 12" B/W, 640 x 480 66.67 Hz 35.0 KHz 30.24 MHz
    13" RGB

    0 0 0 reserved

    0 1 1 VGA 640 x 480 59.94 Hz 31.47 kHz 25.18 MHz

    1 0 0 reserved

    1 0 1 reserved

    1 1 1 no monitor connected

    * 640 x 480 displays are supported at 8 bits/pixel with 512K VRAM and 16
    bits/pixel with 1 MB of VRAM

    Note: The monitor ID pins 3, 2, and 1 refer to pins 10, 7, and 4 on the
    DB-15 external video port.

    The monitor ID must be asserted in the monitor by grounding lines for zeros
    and leaving no connection for ones. No co nects are pulled high by pullup
    resistors on the Performa 600 logic board.

    Standard Macintosh video timing calls for a 30.24 MHz pixel clock for 640 x
    480 displays. Performa 600 deviates from the standard by using the CPU
    clock, at 31.3344 MHz, as a pixel clock for those displays. This results in
    an extra 32 pixels per horizontal line. The active pixels are center in the
    active video field with 16 extra pixels on each side. Horizontal and
    vertical scan rates remain unchanged. The effect of this change is that
    square pixels are visually 3% thinner. The 12" monochrome display
    compensates for this aberration, but the 13" color display does not. Monitor
    ID 2 is grounded within Performa 600, which triggers the 12" monochrome
    display to realize that it is connected to a Performa 600 and allows the
    monitor to compensate for the slightly different timing.

    VGA monitors use the monitor ID of 011 which is the same as the two-page
    monochrome monitor. VGA monitors use the extended monitor sense codes
    which is enabled by tying the ID 3 and ID 2 lines together at the monitor
    end. The extended sense for a VGA monitor is 01 01 11.

    One other anomaly in Performa 600 is that it does not support 1 bit/pixel
    mode on 512 x 384 monitors.



Document Information
Product Area: Computers
Category: Macintosh Performa 200 through 640 Series
Sub Category: Macintosh Performa 600

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