DSPP: PA-RISC Architecture - System documentation for 32- and 64-bit PA-RISC processors. Hewlett-Packard Development Company, L.P. - http://h21007.www2.hp.com/dev/technologies/topic/1,2608,10403,00.html
My HP 9000 712/60 Gecko Workstation - Article on a PA-RISC-based HP 9000, its unique HP Color Recovery technology, and NeXTSTEP. Byte Cellar. - http://www.bytecellar.com/archives/000040.php
The OpenPA Project - Help and information for users of PA-RISC HP 9000 workstations and servers. Topics: hardware, computers, software, news. - http://openpa.net/
PA-RISC Family - Growing article, with links to many related topics. [Wikipedia] - http://en.wikipedia.org/wiki/PA-RISC_family