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ISA I/O Address Map
Table 6–1 ISA Interrupts
Interrupt Number Interrupt Source
IRQ13
IRQ14
IRQ15
1
The # symbol indicates an active low signal.
6.2 ISA I/O Address Map
Table 6–2 lists the Alpha 164UX ISA I/O space address mapping.
Table 6–2 ISA I/O Address Map
Range (hex)
060-060
064-064
1F0-1F7
2F8-2FE
378-37B
3F0-3F5
3F6-3F6
3F7-3F7
3F8-3FE
6.2.1 Flash ROM Address Map
The flash ROM is mapped to three regions of memory. Access to the first two
regions is RO. The first two regions provide the software necessary to initialize the
system and transfer execution to the next level of software. When power is turned
on, address ranges 0 to 00.00FF.FFFF and 0F.FC00.0000 to 0F.FFFF.FFFF are
enabled. After the system has been initialized, these two address ranges are disabled.
Byte mode is then enabled in the 21164 and 21174. Byte mode is the only way to
access the flash ROM in address range 87.C000.0000 to 87.FFFF.FFFF. 21164 byte
Interrupts and ISA Bus Addresses
6–2
Available
IDE
IDE
Usage
i8042 PRT
i8042 PRT
ATAPI
Serial port—COM2
Parallel Port—LPT2
Floppy
ATAPI
Floppy
Serial port—COM1
(Sheet 2 of 2)
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