Dell Dimension XPS 50 Reference Manual page 150

B-16 Dell Dimension XPS Txxx and Txxxr Systems Reference and Troubleshooting Guide
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xxxx–xxxx Reserves the specified UMB (for example C800 – CBFF) for
use by legacy ISA devices. Settings are Available (default)
and Reserved.
IRQ n Reserves the specified IRQ for use by legacy ISA devices.
Settings are Available (default) and Reserved.
NOTE: The Glossary in the system Help defines abbreviations and acronyms.