Specifications

4–12 Functional Description 9 March 1999 – Subject To Change
Interrupts
Table 4–2 AlphaPC 164LX System Interrupts
21164 Interrupt IPL
1
1
IPL = interrupt priority level (fixed).
Suggested Usage AlphaPC 164LX Usage
cpu_irq<0> 20 Corrected system error Corrected ECC error and
sparse space reserved encod-
ings detected by the 21174
cpu_irq<1> 21 — PCI and ISA interrupts
cpu_irq<2> 22 Interprocessor and timer
interrupts
TOY clock interrupt
cpu_irq<3> 23 — Reserved
pwr_fail_irq 30 Powerfail interrupt Reserved
sys_mch_chk_irq 31 System machine check
interrupt
SIO NMI and 21174 errors
mch_hlt_irq — Halt Reserved
Table 4–3 ISA Interrupts
Interrupt
Number Interrupt Source
IRQ0 Internal timer
IRQ1 Keyboard
IRQ2 Interrupt from controller 2
IRQ3 COM2
IRQ4 COM1
IRQ5 Available
IRQ6 Diskette (floppy)
IRQ7 Parallel port
IRQ8#
1
Reserved