Running the System Diagnostics 5-13SubtestsThe eight subtests in the Video Test Group and the videofunctions they test follow:• Video Memory TestChecks the read/write capability of video memory invarious video modes.• Video Hardware TestChecks the cursor registers and the horizontal andvertical retrace bit registers in the video controller.• Text Mode Character TestChecks the video subsystem’s ability to present datain text modes.• Text Mode Color TestChecks the video subsystem’s ability to present colorin text modes.• Text Mode Pages TestChecks the video subsystem’s ability to map andpresent all available video pages on the screen, onepage at a time.• Graphics Mode TestChecks the video subsystem’s ability to present dataand color in graphics modes.• Color Palettes TestChecks the video subsystem’s ability to display all ofthe available colors.• Solid Colors TestChecks the video subsystem’s ability to showscreens full of solid colors. Allows you to check formissing color subpixels.Many of these tests display characters or graphics on thescreen for you to verify. Samples of these screens areshown in Appendix B, “Diagnostic Video Tests.”NOTE: The default limit for testing super video graphicsarray (SVGA) modes is No. If you are testing an externalmonitor, change the default to Yes.Why Run a Video Test?Many of the symptoms that would prompt you to run asubtest in the Video Test Group are obvious, because themonitor 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 thesoftware or caused by a hardware change. You shouldalso try running all of the software support utilities pro-vided for the monitor and the video subsystem.If the following symptoms still occur, run the appropriatetest(s) as follows:• If the monitor shows a partially formed or distortedimage, run all of the subtests in the Video TestGroup.• If the alignment of text or images is off, regardless ofthe program you are running, run the Text ModeCharacter Test, Text Mode Pages Test, and GraphicsMode Test.• If you have a color monitor or a program that runs incolor, but the color is intermittent or not displayed atall, run the Text Mode Color Test, Color PalettesTest, and Solid Colors Test.• If the monitor malfunctions in one mode but worksfine in another (for example, text is displayed cor-rectly, but graphics are not), run the Text ModeCharacter Test, Text Mode Color Test, Text ModePages Test, and Graphics Mode Test.Keyboard Test GroupThe subtests in the Keyboard Test Group verify the cor-rect operation of the keyboard and the keyboardcontroller chip.SubtestsThe five keyboard subtests and the keyboard functionsthey test follow:• Keyboard Controller TestConfirms the ability of the keyboard controller chipto communicate with the keyboard and the program-ming of the controller chip
