TITLE
    Macintosh: Scan Rates for Monitors
Article ID:
Created:
Modified: 		4815
12/13/89
8/9/00
TOPIC
DISCUSSION

    Here are two terms you need to understand when reading the tables:

    Scan Rates
    The scan rate is the time it takes a monitor's electron gun to move across one line of the screen or repeat one entire screen. These values are known as the horizontal and vertical scan rates, respectively. The monitor scan rate is the number of times a screen is redrawn each second. Computer display scan rates differ from standard video scan rates.

    Interlaced versus Non-Interlaced Scans
    Apple monitors use a non-interlaced, or progressive, scan. Interlacing is a technique used on character-based displays to create solid character text. It is also used on home television sets (the dominant standard in the United States being NTSC). Using alternate scan lines, the monitor performs high-speed retraces to create the illusion that the monitor has twice as many lines as it does. A major drawback of interlaced displays is their tendency to noticeably flicker thin horizontal lines, lines that are frequently used on the Macintosh interface.

    The non-interlaced format used on Apple Macintosh monitors means that the horizontal and vertical scan rates are timed to cause the display electron guns to produce even progressively horizontal scans. The non-interlaced scan format helps prevent the flickering that you can see on some types of monitors.
    Built-in monitors Vertical (Hz) Horizontal (KHz)
    Macintosh 128K 60.15 22.25
    Macintosh 512K 60.15 22.25
    Macintosh 512Ke 60.15 22.25
    Macintosh Plus 60.15 22.25
    Macintosh SE 60.15 22.25
    Macintosh SE/30 60.15 22.25
    Macintosh Classic 60.15 22.25
    Macintosh Classic II 60.15 22.25
    Macintosh Color Classic 60.15 24.48
    Macintosh LC 520 66.7 35
    Macintosh LC 550, 575, 580 66.7 35
    Power Macintosh 5200/75 60-75 35-50
    Power Macintosh 5260/75 60-75 35-50
    Power Macintosh 5400/180
    Power Macintosh 5400/200
    Power Macintosh 5400/225     		60-75 35-50
    Power Macintosh 5500/225 60-75 35-50
    Power Macintosh G3 All-in-one 59.9-85 31.469-56.476
    Apple and Macintosh Monitors Vertical (Hz) Horizontal (KHz)
    Apple 21-in. Color Display 75 68.7
    Apple Two-Page Monitor 75 68.7
    Apple 16-in. Color Display 75 50
    Apple Portrait Display 75 68.9
    Apple AudioVision 14 Display 66.7 35
    Macintosh (14-in.) Color Display 66.7 35
    Basic (14-in.) Color Monitor 59.94 31.5
    Performa Plus Display 66.7 35
    Performa Display 66.7 35
    AppleColor High-Res RGB Monitor 66.7 35
    AppleColor High-Res Mono Monitor 66.7 35



    Multiple Scan Monitors:

    Apple Macintosh multiple scan monitors let you customize and adjust the size and position of the displayed image.

    Apple Multiple Scan 15 display
    Mode Resolution Vertical (Hz) Horizontal (KHz)
    VGA 640x480 60 31.77
    Macintosh 640x480 66.7 35
    SVGA 800x600 72 48.1
    SVGA 800x600 60 37.9
    Macintosh 832x624 75 49.7
    1024x768 1024x768 70 56.5


    Apple Multiple Scan 17 display
    Mode Resolution Vertical (Hz) Horizontal (KHz)
    VGA 640x480 59.95 31.47
    Macintosh 640x480 66.7 35
    VESA 640x480 75 37.5
    VESA 800x600 75 46.9
    SVGA 800x600 55.98 35.16
    800x600 800x600 60 37.8
    Macintosh 832x624 75 49.73
    Macintosh 1024x768 75 60.2
    1024x768 1024x768 60 48.3


    Apple Multiple Scan 20 display
    Mode Resolution Vertical (Hz) Horizontal (KHz)
    VGA 640x480 59.95 31.47
    Macintosh 640x480 66.7 35
    VESA 640x480 75 37.5
    VESA 800x600 75 46.9
    Macintosh 832x624 75 49.73
    Macintosh 1024x768 74.93 60.24
    VESA 1024x768 75 60.02
    Macintosh 1152x870 75 68.7
    VESA 1280x1024 75 79.98


    In some cases, it may be necessary to reset the display settings of a multiple scan monitor to their factory defaults. To reset these monitors, hold down Control button (which has the circle symbol above it), while pressing the Reset button (which has the triangle symbol).

    Most of the time, just pressing the Reset button resets the display settings. However, pressing Control-Reset resets the CPU inside the Multiple Scan 17 Display and Multiple Scan 20 Display.

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

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