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support.dell.com Basic Troubleshooting 3-9
result when other programs require use of all or part of the memory already occupied
by these TSR programs.
Typically, the operating system’s start-up files contain commands to start TSR
programs when you boot the computer. If you suspect that one of these TSR
programs is causing a memory conflict, remove the commands 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 commands 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 information behind, even though
you have exited from them. As a result, other programs cannot run. Rebooting the
computer can confirm whether or not these programs are the cause of the problem.
Other programs use specialized subroutines called drivers that can cause problems in
the computer. For example, 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—for example, the creation of a boot file made
especially for that program. 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 conflict, check the documentation for the default IRQ line
setting for each installed device. Then consult Table 3-2 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 the computer’s serial port is COM1.
Table 3-2. Default 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 Cascade to second interrupt controller
IRQ3 Reserved
IRQ4 Used by the communications port (COM1)
IRQ5 Used by the internal modem, audio controller, and USB
NOTE: For the full name of an abbreviation or acronym used in this table, see the Glossary
in the system Help.