Input Errors
If a specific key or set of keys is pressed at the wrong time, a program may give you unexpected results. See the documentation that came with the application program to make sure that the values or characters you are entering are valid.
Make sure that the operating environment is set up to accommodate the programs you use. Keep in mind that whenever you change the parameters of the computer’s operating environment, you may affect the successful operation of the programs. Sometimes, after modifying the operating environment, you may need to reinstall a program that no longer runs properly.
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 the system can confirm whether these programs are the cause of the problem.
There are also programs that use specialized subroutines called device drivers that can also cause problems with the computer system. For example, a variation in the way the data is sent to the 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 alter- native method of running that particular
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 expansion card. Then consult Table
Table 4-1. Default IRQ Line Assignments
IRQ Line | Used/Available |
|
|
IRQ0 | Used by the system timer |
IRQ1 | Used by the keyboard to signal that |
| the output buffer is full |
IRQ2 | Used by interrupt controller 1 to |
| enable IRQ8 through IRQ15 |
IRQ3 | Used by serial port 2 |
IRQ4 | Used by serial port 1 |
IRQ5 | Available |
IRQ6 | Used by the diskette/tape drive con- |
| troller |
IRQ7 | Used by the parallel port |
IRQ8 | Used by the RTC |
IRQ9 | Available |
IRQ10 | Available |
IRQ11 | Available |
IRQ12 | Used by the mouse port |
IRQ13 | Used by the math coprocessor (if |
| applicable) |
IRQ14 | Available |
IRQ15 | Available |
|
|
NOTE: For the full name of an abbreviation or acronym used in this table, see the abbreviation and acronym list.