Specifications

System Registers 7-65

TLINTRSUM0–1—Interrupt Source Registers

ddress

ccess

BB + 1180, BB + 11C0

R/W

The DECchip 21164 has seven interrupt lines. They are as follows:

1. IRQ<3:0> - Interrupt request lines mapping to IPL17:IPL14

2. SYS_MCH_CHK_IRQ - Machine check interrupt request

3. MCH_HLT_IRQ - Machine halt interrupt request

4. PWR_FAIL_IRQ - Power fail interrupt request

Multiple interrupts from different devices may be targeted at the

same interrupt request pin of the CPU. For example, two I/O device

may request service at IPL14, while an on-module DUART interrupt

may occur at the same time. All these interrupts would be targeted

to the IRQ<0> pin of the CPU.

DECchip 21164 PALcode reads the TLINTRSUM register to deter-

mine the source of any outstanding interrupts.

31 43 0765 12

BXB-0510-93

INTIM_INTR

IP_INTR

IPL17_INTR

IPL16 _INTR

IPL15_INTR

IPL14 _INTR

DUART0_INTR

Ctrl/P HALT

HALT

29 28 27 26 22 21 17 16 15 14 13 12 11

ILP17 IPL16 IPL 15 IPL14

Node 8

Node 7

Node 6

Node 5

Node 4