Specifications

Hardware Configuration
2–52
2.17.5 Interrupt and DMA Channel Usage
The AT bus provides several interrupt and DMA control signals. When you expand the system with
MiniModule products or plug-in cards that require either interrupt or DMA support, you must select
which interrupt or DMA channel to use. Typically this involves switches or jumpers on the module. In
most cases, these are not shared resources. It is important that you configure the new module to use
an interrupt or DMA channel not already in use. For your convenience, Tables 2-39 and 2-40 provide
a summary of the normal interrupt and DMA channel assignments on the Little Board/486i.
Interrupt Function
IRQ0*
IRQ1*
IRQ2*
IRQ3
IRQ4
IRQ5
IRQ6
IRQ7
ROM BIOS clock tick function, from Timer 0
Keyboard interrupt
Cascade input for IRQ8-15
Serial 2
Serial 1
Available
Floppy controller
Parallel port (option)
IRQ8*
IRQ9**
IRQ10
IRQ11
IRQ12
IRQ13*
IRQ14
IRQ15
Reserved for battery-backed clock alarm
Ethernet interface default
Serial 4 (option)
SCSI interface default
Serial 3 (option)
Reserved for coprocessor
IDE hard disk controller
Available
* Unavailable on PC/AT bus.
** Corresponds to IRQ2 on a PC’s expansion bus.
Table 2-39 Interrupt Channel Assignments