Atari 1200 XL, Руководство по обслуживанию на месте

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GRAY BAR TEST
This test verifies that the GTIA is generating Lum 0, 1 and 2. L3 is not tested. Press the
command letter G and then RETURN to activate this test.
Figure 3-5 illustrates the screen display of the Gray Bar Test. The screen is divided into eight
equal sized horizontal bars. The bar at the top of the screen should be black and subsequent
bars should progress to white at bar eight. The bars should lighten in even shades. The screen
should be steady and unchanging. These lines may have minor glitches at their edges. A thin
white line should always appear just over the top (black) bar. No color should appear anywhere
on the screen. The areas above the top (black) bar and below the bottom (white) bar are of no
importance to this test. This test should be left on for at least 60 seconds to ensure that there is
no "flashing" of color or shifting of the gray bars.
Figure 3-5. Gray Bar Test Screen
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DISPLAY OPTIONS
This function, which is not a test, displays a diagnostic matrix when used in conjunction with
the RAM TEST.
Figure 3-6. Display Options Screen
1200XL Home Computer
Field Service Manual
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