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Details on Individual Diagnostic Tests
This section explains each test within the diagnostics program. Each test is listed along with its
command-line file name. A brief description of the test, command-line parameters, valid
keystrokes available during the test, and corresponding failure messages with error codes are
also given.
Note, the term “flushed” that is used in the keystrokes sections indicates that the key is read from
the key buffer and then discarded.
Test All
This is an easy way to run all the tests in sequence. However, looping does not work as
expected with the Test All selection. For example, if three tests are tagged for looping and Test
All is initiated, then the first two tests are executed only once. The last test in the sequence is
the only test that will be looped.
Display - (DISP.COM)
The Display test executes a sequence of patterns on the screen:
1. Tests video RAM, which leaves vertical lines in groups of 4.
2. Draws a box around the outside edge of the display, filling the center with black.
3. Fills the entire display with white.
4. Fills the entire display with a 10-pixel checkerboard.
5. Fills the display with horizontal lines on every 4
th
pixel, then steps the lines 3 times.
6. Fills the display with vertical lines on every 4
th
pixel, then steps the lines 3 times.
7. Draws 16 horizontal bars of different colors.
8. Draws 16 vertical bars of different colors.
9. Draws 4 horizontal shaded bands (red, green, blue, and white) with vertical tick marks.
DOS Parameter Explanation
1, 0, or none Wait for a key after each display pattern
2 or greater Don’t wait for a key
Valid Keystrokes Action
any key When the DOS parameter is set to wait for
a key, any key will step to the next display
pattern; the only way to exit the test is to
step through all patterns.
Esc Aborts the test and all other keys are
flushed.
Failure Message Error Code Meaning
User Aborted 1 User aborted test.
Failed 2 Video RAM is bad.