TITLE
    Apple High Resolution RGB Monitor: Technical Q&A
Article ID:
Created:
Modified: 		8439
9/11/91
9/16/91
TOPIC




    I have some technical questions about the Apple 13-inch High-Resolution RGB
    monitor:

    1) What is the pixel size?

    2) What's the pixel interleave?

    3) How much time does it take to turn pixels on and off?

    4) What's the wavelength range from blue to red?

    5) What's the maximum brightness of the screen?

    6) Can the Macintosh hardware handle programming to command video
    cards to display objects on the desktop (circles, squares, and so
    on, with different colors?)

DISCUSSION


    1) Pixel size (also known as "dot pitch" or "grill pitch") is 0.25mm.

    2) There are no specifications on pixel interleave.  If the request is
    for the sequence of placing pixels on the screen, then the following
    discussion should assist in understanding how the monitor works.

    Video cards that drive the AppleColor High Resolution RGB Monitor
    use an approximation of the RS343 display signal.  (RS video standards
    are set by the Electronic Industries Association.) The RS343 display
    standard is essentially a monochrome video signal combined with a
    composite sync signal (horizontal and vertical scan control) with
    timings that produce a non-interlace, or progressive, scan. This means
    that the horizontal and vertical scan rates are timed to cause the
    display electron guns to produce even progressively horizontal scans.
    This is by comparison to the interlaced video standards. The importance
    of the RS343 standard is its provision for a timing and voltage level
    signal that allows the display and generation of high resolution video.

    While the Macintosh II version of the RS343 signal varies somewhat,
    it essentially follows the guidelines necessary for connection to RS343
    display devices. The major differences are:

    · the separate TTL level composite sync signal found on pin 3
    · the separate video lines used to produce RGB color
    · a vertical scan rate of 66.67Hz to reduce screen flicker
    · a voltage white level of 1 volt for its red and blue signals and
    1.3 volts on its green signal

    RS343 provides for a 60hz signal but has been changed to 66.67Hz on the
    Macintosh II Video Card, to prevent the screen flicker visible at 60Hz.

    3) The pixel clock frequency is 30.24 MHz. The only other specification
    that would appear to relate to this issue is phosphor persistence,
    which is rated by phosphor vendors as medium-short.

    4) Due to contractual agreements, this information is not available.

    5) Luminance level is 20 footlamberts with the brightness control in
    the center detent position. With the brightness control in the
    full-open position, the luminance level is 25 footlamberts.

    6) The Macintosh firmware (the Macintosh Toolbox) has QuickDraw
    routines to handle the creation of the desired objects. Typically, the
    video cards are not "commanded" to display objects.  Video cards will
    display the information that is placed in the video buffer. QuickDraw
    is used to place the information in that video buffer.  The only
    possible exception is when a graphics coprocessor card is placed in the
    Macintosh.  However, the Macintosh interface to these specialized video
    cards is still through QuickDraw.  Although, now QuickDraw is being
    executed by the graphics coprocessor, not by the system's primary CPU.

Copyright © 2000 Apple Computer, Inc. All rights reserved.