Compaq 164SX - Manual (Page 50)

4–10 Functional Description
Interrupts
register. Interrupts latched in the interrupt request register can be reset individually
by writing a 1 to the bit to be cleared. This immediately clears the bit to avoid taking
a second interrupt. Figure 4–5 shows the interrupt request register.
Figure 4–5 Interrupt Request Register
The interrupt mask register provides individual mask bits for each interrupt.
Table 4–2 lists the AlphaPC 164SX system interrupts, and Table 4–3 lists the ISA
interrupts.
1 IPL = interrupt priority level (fixed)
Table 4–2 AlphaPC 164SX System Interrupts
21164PC Interrupt IPL
1
Suggested Usage AlphaPC 164SX Usage
cpu_irq[0] 20 Corrected system error Reserved
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 NMI and 21174 errors
mch_hlt_irq — Halt Reserved
31 24 23 20 19 16 15 12 11 08 07 06 05 03 02 01 00
63 62
A2 A3 A1 A0 B2 B3 B1 B0 C2 C3 C1 C0 D2 D3 D1 D0 06 07 05 04 02 03 01 00
Reserved
NMI INT
Halt INT
Reserved
Real-time CLK_INT
ISA_INT
PCI_INT A
n
PCI_INT B n
PCI_INT C n
PCI_INT D n
CONFIG[7:0]
Reserved
21174 CLK_INT
ERROR INT
61 32