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.Then, replace any units removed prior to the one that caused the Chapter 5 Troubleshooting the System313system to start.This ensures that there were not multiple badparts.If all the parts have been replaced, and the unit still doesnot function properly, the diagnostic software is suspect.Using ROM-Based DiagnosticsIn cases where the system is unable to load information from afloppy disk, ROM-based diagnostic programs are available thatcan be used to check out the partially dead system.In other sys-tems, the diagnostic chips are usually substituted for the systemboard s ROM BIOS chip.Several companies offer disk-based and ROM-based diagnosticspackages for troubleshooting computer problems.Some are bet-ter than others.As a group, ROM-based diagnostics packages arebetter than disk-based packages simply because they require muchless of the system to be operable for use.Disk-based programsrequire that almost all the system be functional before they can beused.Some versions of the AMI BIOS come with an extensive set ofdiagnostic routines built into the ROM package.Therefore, youcan use the diagnostic routines without removing the systemunit s outer cover.These routines can be entered through theBIOS CMOS Setup menu.To invoke the diagnostic program,turn on the computer and wait for the message Press DEL if youwant to run SETUP or DIAGS and press the DEL key.After enter-ing the CMOS Setup screen, simply move the screen cursor to theRun Diagnostics position and press the ENTER key.The BIOS rou-tine responds by placing its diagnostics selection menu, illustratedin Figure 5.5, on the monitor screen.You select the section to test,along with the specific test to run, by using the ARROW keys.The diagnostic menu screen is divided into three major portions:.AMI ROM Diagnostics header.Field for listing available procedures and tests.List of present devices known to the system A+ Certification Training Guide314Figure 5.5ROM DIAGNOSTICS, (C) 1986,American Megatrends Inc.Fri,Sep 20,1991 13:50:36The CMOSdiagnosticsHard Disk Floppy Keyboard Video Miscellaneousmenu.Hard Disk FormatAuto InterleaveMedia AnalysisPerform TestSeek TestRead/Verify TestCheck Test Cyl.Force Bad TracksHard Disk Floppy Comm.Display Printer Memory CO-procC: A: 360KB #03F8 Mono #03BC REAL 640KB Absent#0378 EXTD 1048KBPrev/Next Window - Move Bar - Select - Exit Diag -Preformat Hard DiskAt the top of the screen is the AMI ROM Diagnostics header.Thisheader contains the BIOS version number, the computer s cur-rent time and date information, and five headings that can beselected for diagnostic operations.These topics include Hard-DiskDrive procedures and test functions, Floppy-Disk Drive proce-dures and test functions, Keyboard tests, Video display tests, andMiscellaneous port tests.When the highlighted cursor is moved to one of the header top-ics, a listing of the available procedures and tests appears in thesection of the screen underneath the topic.At the bottom of thescreen, the program displays a list of the devices that it knows arepresent in the system.Directions for navigating through the pro-gram are also presented at the bottom of the page.When you select a test listed below one of the diagnostic topics,firmware test routines stored in the ROM BIOS are executed.These diagnostic programs can be used to determine the func-tionality of the computer s sub-systems.The routines are menu-driven and enable you to select a specific test to execute.Theyalso provide information about devices installed in the system. Chapter 5 Troubleshooting the System315The Printer Adapter test checks the signals of the parallel port.During the test, a printer should be connected and the powershould be ON.This test reports any abnormalities in the printerport status signals, such as whether the printer is loaded with pa-per.The parallel loopback plug is normally used to simulate the pres-ence of a parallel printer.The communication port test requires that a serial port loopbackplug be installed in the port connector.This plug simulates anoth-er communication port connection
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