Beside the excellent hpmuseum.net please note the superb website by Paul Weissmann et al., openpa.net.
BTW a snapshot of my HP 9000 production machines running HP-UX legacy research applications, a C360 ('Cranach') and a K580 ('Kepler')---their manufacturing quality and reliability is only excelled by the ~25 year older HP 46 on the left :-)
http://www.itp.uni-hannover.de/~paech/P1030963e.jpg
It's a pity that HP has never developed a HP 28/48 compatible RPL interpreter or compiler for HP-UX beside their great FORTRAN and C/C++ products...
Martin
Edited: 6 May 2012, 9:38 a.m.