•The speaker no longer functions. The problem could be a failure of the system timers as well as a failure of the speaker itself. Run the Timers Test, followed by the Speaker Test.
•If a peripheral device appears to malfunction, run the Interrupt Controller Test.
•A spreadsheet program or other type of mathemat- ical application runs abnormally slow, generates error messages concerning calculations or opera- tions, runs incorrectly, or generates incorrect results, or a proven piece of the program appears to mal- function and you confirm that the software itself is not at fault. You can confirm that the software is not at fault by moving the program to another computer and running it there.
•The computer periodically locks up, especially at different places and times in different programs.
•The computer halts in the middle of performing cal- culations or complex mathematical operations.
Video Test Group
The subtests in the Video Test Group verify the proper operation of the video controller and the video control circuitry installed in the computer. These subtests check for the correct operation of the readable registers in the video circuitry and the controller. They write, read, and verify data patterns in the cursor registers of the control- ler. The Video Test Group also tests all the video memory and provides additional subtests to test the color features of a color monitor.
NOTE: Most of the subtests are interactive; that is, you must respond before the diagnostics continue to the next subtest.
Subtests
The subtests in the Video Test Group and the video func- tions they confirm follow:
•Video Memory Test
Checks the read/write capability of video memory 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. Allows you to check for missing color subpixels.
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 super video graphics array (SVGA) modes is No. If you are testing an external monitor, change the default to Yes.
Why Run a Video Test?
Many of the symptoms that would prompt you to run a subtest in the Video Test Group are obvious, because the monitor is the visual component of the computer system. Before you run the Video Test Group or any of its sub- tests, you should make sure that the problem is not in the software or caused by a hardware change. You should also try running all of the software support utilities pro- vided for the monitor and the video subsystem.
