Compaq 164LX Manual De Usuario

6–2

Interrupts and ISA Bus Addresses

ISA I/O Address Map

6.2 ISA I/O Address Map

Table 6–2 lists the AlphaPC 164LX ISA I/O space address mapping.

IRQ13

Available

IRQ14

EIDE

IRQ15

EIDE

The # symbol indicates an active low signal.

Table 6–2 ISA I/O Address Map

Range (hex)

Usage

000-00F

8237 DMA #1

020-021

8259 PIC #1

040-043

8253 timer

060-061

Ubus IRQ12 and NMI control

070

CMOS RAM address and NMI mask register

080-08F

DMA page registers

0A0-0A1

8259 PIC #2

0C0-0DF

8237 DMA #2

2F8-2FF

Serial port—COM2

370-377

Secondary diskette (floppy)

3BC-3BF

Parallel port—LPT1

3F0-3F7

Primary diskette (floppy)

3F8-3FF

Serial port—COM1

800

FLASH_ADR19 register

801

AlphaPC 164LX configuration register

804-806

PCI interrupt registers

Table 6–1 ISA Interrupts (Continued)

Interrupt Number Interrupt Source