Ampro Corporation 486E manual Interrupt and DMA Channel Usage, Interrupt Function

Little Board™/486e Technical Manual

Interrupt and DMA Channel Usage

The AT bus provides several interrupt and DMA control signals. When the system is expanded with MiniModule products or plug-in cards that require either interrupt or DMA support, interrupt or DMA channels must be specifically selected. This typically involves setting switches or adding jumpers on the module. In most cases, these are not shared resources. It is important to configure the new module to use an interrupt or DMA channel not already in use. Table 2–50 and Table 2–51 provide a summary of the normal interrupt and DMA channel assignments on the Little Board/486e CPU.

	Table 2–50. Interrupt Channel Assignments
Interrupt		Function
IRQ0*		ROM BIOS clock tick function, from Timer 0
IRQ1*		Keyboard interrupt
IRQ2*		Cascade input for IRQ8-15
IRQ3		Serial 2
IRQ4		Serial 1
IRQ5		Secondary Parallel port (option) / Serial 4 (option)
IRQ6		Floppy controller
IRQ7		Primary Parallel port (option) / Serial 3 (option)
IRQ8*		Reserved for battery-backed clock alarm
IRQ9**		Ethernet interface default**
IRQ10		Serial 4 (option)
IRQ11		Serial 3 (option)
IRQ12		Available
IRQ13*		Reserved for coprocessor *
IRQ14		IDE hard disk controller
IRQ15		Available

* Unavailable on the PC/104 bus.

** Corresponds to IRQ2 on PC’s expansion bus.

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