Ampro Corporation 486E - Manual (Page 86)

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 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*
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 (option)
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.