Tests the RAMDAC in three phases. In the first phase the RAMDAC CLUT (Color LookUp Table) is tested using simple write/read patterns to determine if there are any bad bits in CLUT.
The data patterns used are:
In the second phase, four different patterns are drawn on the screen. Each pattern stays on the screen for approximately three seconds. The four patterns are listed below. For each pattern the signature is captured and compared with the signature obtained for the same pattern on a known good board. This test verifies that all the different data paths within the RAMDAC are functioning properly.
Patterns drawn on screen:
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Red ramp with cursor at top-left corner of the screen
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Blue ramp with cursor at top-right corner of the screen
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Green ramp with cursor at bottom-left of the screen
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Grey ramp with cursor at bottom-right of the screen
In the last (third) phase of the RAMDAC test the Vertical Retrace Interrupt is tested for 300 interrupts.
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