Dell Latitude LM - Manual (Page 69)

Running the Dell Diagnostics 4-13
Why Run a RAM Test?
Faulty memory can cause a variety of problems that may
not, at first glance, appear to be happening in RAM. If the
computer is displaying one or more of the following
symptoms, run both the subtests in the RAM Test Group
to verify that the memory is not at fault:
• A program is not running as usual, or a proven piece
of software appears to malfunction and you confirm
that the software itself is not at fault. (You can con-
firm that the software is functioning properly by
moving it to another computer and running it there.)
• The computer periodically locks up (becomes un-
usable and must be rebooted), especially at different
places and times in different programs.
Subtests
Two subtests are available for RAM: the Quick Test and
the Comprehensive Test. The Quick Test performs an
address check to determine whether the computer is
properly setting and clearing individual bits in RAM, and
whether the RAM read and write operations are affecting
more than one memory address location at one time. This
subtest checks all available RAM. The Comprehensive
Test also performs an address check, as well as the
following:
• Data pattern checks, to look for RAM bits that are
stuck high or low, short-circuited data lines, and
some data pattern problems that are internal to the
memory chips
• A parity check that verifies the ability of the memory
subsystem to detect errors
• A refresh check, to verify that the dynamic RAM
(DRAM) is being recharged properly
S
ystem Set Test Group
The subtests in the System Set Test Group check the
computer’s basic system board components and verify
their related functions.
Why Run a System Set Test?
The System Set subtests double-check many system
board components, such as the computer’s I/O circuitry, that
are tested by other test groups or subtests in the diagnostics.
You should run the System Set Test Group if you are having
a problem and cannot isolate the failure or malfunction to a
particular system board component.
The System Set Test Group also verifies the proper oper-
ation of other computer components, such as the speaker,
that are not tested elsewhere in the diagnostics.
The following symptoms usually suggest a problem with
a component or subassembly that warrants running a Sys-
tem Set subtest:
• A program is not running as usual, or a proven piece
of software appears to malfunction and you confirm
that the software itself is not at fault. (You can con-
firm that the software is functioning properly by
moving it to another computer and running it there.)
• A PC Card you previously accessed can no longer be
accessed.
• The computer periodically locks up, especially at
different places and times in different programs.
• Parity errors or page fault failures (any error mes-
sage that contains the word parity or page fault) occur
at any time during operation. These errors are usually
accompanied by a reference to an address, which you
should record on a copy of the Diagnostics Checklist
found in Chapter 5.
• Correcting errors in the system configuration infor-
mation does not resolve a problem.
• The computer’s clock/calendar stops.
• 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 System Timers Test,
followed by the System Speaker Test.
• If a peripheral device appears to malfunction, run the
Interrupt Controllers Test. If the computer fails the
test, the problem lies with the interrupt controller; if
the computer passes, then the problem lies with the
peripheral device.
• A spreadsheet program or other type of mathemati-
cal 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