Dell Latitude LM - Manual (Page 71)

Running the Dell Diagnostics 4-15
Character Test, Text Mode Pages Test, and the Graphics
Mode Test.
• If the color on the display or external monitor is
intermittent or not displayed at all, run the Text
Mode Color Test, the Color Palettes Test, and the
Solid Colors Test.
• If your display or external monitor malfunctions in
one mode but works fine in another (for example,
text is displayed correctly, but graphics are not), run
the Text Mode Character Test, Text Mode Color
Test, Text Mode Pages Test, and the Graphics Mode
Test.
Subtests
The eight subtests in the Video Test Group confirm the
following video functions:
• Video Memory Test
Checks the read/write capability of the video mem-
ory in various video modes
• Video Hardware Test
Checks the cursor registers and the horizontal and
vertical retrace bit registers in the video controller
• Text Mode Character Test
Checks the video subsystem’s ability to present data
in text modes
• Text Mode Color Test
Checks the video subsystem’s ability to present color
in text modes
• Text Mode Pages Test
Checks the video subsystem’s ability to map and
present all available video pages on the screen, one
page at a time
• Graphics Mode Test
Checks the video subsystem’s ability to present data
and color in graphics modes
• Color Palettes Test
Checks the video subsystem’s ability to display all of
the available colors
• Solid Colors Test
Checks the video subsystem’s ability to show
screens full of solid colors, and allows you to check
for missing color pixels
Many of these tests display characters or graphics on the
screen for you to verify. Samples of these screens are
shown in Appendix B, “Diagnostic Video Tests.”
NOTE: The default limit for testing SVGA modes is NO . If
you are testing an external monitor, change the default to
YES .
K
eyboard Test Group
The subtests in the Keyboard Test Group verify the cor-
rect operation of your keyboard and the keyboard
controller chip.
Why Run a Keyboard Test?
Keyboard problems are not always caused by the key-
board. For example, a complete lockup of the computer,
rendering the keyboard inoperable, is probably not caused
by a problem with the keyboard. There are two symptoms
that are likely to be keyboard-related. Sometimes, the config-
uration of a program changes the function of a key or key
combination. Similarly, key configuration programs like
ProKey can change a key’s function. Because these pro-
grams are memory resident, be sure to clear them out of the
computer’s memory before running a subtest in the Key-
board Test Group. (Clear them from memory by booting the
computer from the Dell Diagnostics Diskette.) When these
possibilities have been eliminated, and if the following
symptoms occur, you should run one or more of the subtests
in the Keyboard Test Group:
• When you press a key, the character represented by
that key appears repeatedly; the key seems to be
stuck. Run the Stuck Key Test.
• When you press a key and the response is different
from the usual response or the response you antici-
pated, the key contact may be damaged. Run the
Keyboard Interactive Test.
• When a key does not work at all, run all of the sub-
tests in the Keyboard Test Group.