Not so much a comprehensive guide, but check the
HP Computer Museum
They have pictures, specs and some manuals online for not only the
HP-3000 series, but earlier HP-1000 and smaller systems and peripherals.
Let me 'second' the recomendation for that site. [...]
Yep, lots of good stuff there. In IE7 you can setup a search provider
so that you can search it directly in one click. Pretty handy.
I find the easiest thing to do (particularly when a manual could be
listed in one of serveral places) is to follow the 'documentation' link
from the homepage and then to search that for anything
that might be
You can 'waste' many enjoyable hours reading manuals for things you never
knew existed :-)