Service manual

Running the Dell Diagnostics: Dell Latitude CP
passes, then the problem lies with the peripheral device.
● A spreadsheet program or other type of mathematical application runs abnormally slow,
generates error messages concerning calculations or operations, runs incorrectly, or
generates incorrect results; or a proven piece of the program appears to malfunction
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 halts in the middle of performing calculations or complex mathematical
operations.
Subtests
The 11 subtests in the System Set test group confirm the following computer functions:
● CMOS Confidence Test
Checks the nonvolatile RAM (NVRAM) for accessibility and reliability of data storage by
performing a data pattern check and verifying the uniqueness of memory addresses.
● DMA Controller Test
Tests the direct memory access (DMA) controller and verifies the correct operation of its
page and channel registers by writing patterns to the registers.
● Real-Time Clock Test
Confirms the functionality and accuracy of the computer's real-time clock (RTC).
● System Speaker Test
Checks the functionality of the speaker by generating eight tones.
● System Timers Test
Checks the timers used by the microprocessor for event counting, frequency generation,
and other functions. Only the functions that can be activated by sofware are tested.
● Interrupt Controller Test
Generates an interrupt on each interrupt request (IRQ) line to verify that devices using
that line can communicate with the microprocessor and that the interrupt controller
sends the correct memory addresses to the microprocessor.
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