Dell Latitude Xpi CD - Manual (Page 55)

Troubleshooting Your Computer 3-15
result when other programs require use of all or part of
the memory already occupied by these TSR programs.
Typically, your operating system’s initialization or start-up
files contain commands to start TSR programs when you
boot your computer. If you suspect that one of these TSR
programs is causing a memory conflict, remove the com-
mands that start them from the start-up file. If the problem
you were experiencing does not recur, one of the TSR
programs probably created the conflict. Add the TSR com-
mands back into the start-up files one at a time until you
identify which TSR program is creating the conflict.
Program Conflicts
Some programs may leave portions of their setup infor-
mation behind, even though you have exited from them.
As a result, other programs cannot run. Rebooting your
computer can confirm whether or not these programs are
the cause of the problem.
Other programs use specialized subroutines called device
drivers that can cause problems in your computer. For exam-
ple, a variation in the way the data is sent to an external
monitor may require a special screen driver program that
expects a certain kind of video mode or monitor. In such cases,
you may have to develop an alternative method of running that
particular program—the creation of a boot file made especially
for that program, for example. For help with this situation, call
the support service offered by the manufacturer of the software
you are using.
Avoiding Interrupt Assignment Conflicts
Problems can arise if two devices attempt to use the same
interrupt request (IRQ) line. To avoid this type of con-
flict, check the documentation for the default IRQ line
setting for each installed device. Then consult Table 3-4
to configure the device for one of the available IRQ lines.
NOTE: Installed devices cannot share the same COM
port address. The default address of your computer’s
serial port is COM1.
Table 3-4. IRQ Line Assignments
IRQ Line Used/Available
IRQ0 Generated by the system timer
IRQ1 Generated by the keyboard controller
to signal that the keyboard output
buffer is full
IRQ2 Generated internally by the interrupt
controller to enable IRQ8 through
IRQ15
IRQ3 Available for use by a PC Card unless
the built-in serial port or infrared port
is configured for COM2
IRQ4 Available for use by a PC Card unless
the built-in serial port is configured for
COM1 (the default)
IRQ5 Available for use by the audio control-
ler
IRQ6 Generated by the diskette drive con-
troller to indicate that the diskette drive
requires the attention of the micropro-
cessor
IRQ7 Available for use by a PC Card or audio
controller if the built-in parallel port is dis-
abled
IRQ8 Generated by the system I/O control-
ler’s RTC
IRQ9 Available for use by the PC Card inter-
rupt controller or the audio controller
IRQ10 Available for use by a PC Card or audio
controller unless the Advanced Port Repli-
cator is attached
IRQ11 Available for use by a PC Card unless
the Advanced Port Replicator is
attached
NOTE: For the full name of an abbreviation or acronym used
in this table, see the Glossary in the online System User’s
Guide.