Compaq user manual ISA I/O Address Map, 2lists the AlphaPC 164SX ISA I/O space address mapping

ISA I/O Address Map

Table 6–1 ISA Interrupts	(Sheet 2 of 2)
Interrupt Number Interrupt Source

IRQ13Available

IRQ14EIDE

IRQ15EIDE

1The # symbol indicates an active low signal.

6.2ISA I/O Address Map

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

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

6–2Interrupts and ISA Bus Addresses