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6–2 Interrupts and ISA Bus Addresses
ISA I/O Address Map
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
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
1
The # symbol indicates an active low signal.
IRQ13 Available
IRQ14 IDE
IRQ15 IDE
Range (hex) Usage
060-060 i8042 PRT
064-064 i8042 PRT
1F0-1F7 ATAPI
2F8-2FE Serial port—COM2
378-37B Parallel Port—LPT2
3F0-3F5 Floppy
3F6-3F6 ATAPI
3F7-3F7 Floppy
3F8-3FE Serial port—COM1
Table 6–1 ISA Interrupts
(Sheet 2 of 2)
Interrupt Number Interrupt Source