Little Board™/486e Technical Manual
2–70
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 ty pical ly inv olve s se tting s witch es o r 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 no t alre ady 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*
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
Secondary Parallel port (option) / Serial 4 (option)
Floppy controller
Primary Parallel port (option) / Serial 3 ( opt ion)
IRQ8*
IRQ9**
IRQ10
IRQ11
IRQ12
IRQ13*
IRQ14
IRQ15
Reserved for battery-backed clock alarm
Ethernet interface default**
Serial 4 (option)
Serial 3 (option)
Available
Reserved for coprocessor *
IDE hard disk controller
Available
* Unavailable on the PC/104 bus.
** Corresponds to IRQ2 on PC’s expansion bus.