Special Consideration for Base System Peripherals

Interrupts may also originate in embedded legacy hardware, such as an I/O Controller Hub or Super I/O device. Some of the typical legacy devices required in such systems include:

  • Serial ports

  • Parallel ports

  • Keyboard and Mouse Controller

  • System Timer

  • IDE controllers

These devices typically require a very specific IRQ line, which allows legacy software to interact with them correctly.

Using the INTx messages does not guarantee that the devices will receive the IRQ assignment that they require. Many different approaches and strategies may be employed to ensure they get the IRQs required. Following is an example system that supports legacy interrupt assignment.

Example System

Figure 9-14 on page 354 illustrates ...

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