From a hardware point of view an HP 16505A is exactly the same thing as an HP 712/60, 712/80, or 712/100 workstation, except for the product label on the front, and the 16505A comes standard with a floppy drive while it is optional on the 712 workstation.
The 712/60 and 712/80 have four SIMM slots and support up to 128MB of main memory using A2575-60001 32MB SIMMs, while the 712/100 has six SIMM slots and supports up to 192MB of main memory.
[For comparison, the 16700A/16702A have either 64MB or 160MB (with Opt 003) of main memory, while the 16700B/16702B have either 128MB or 256MB (with Opt 003) of main memory.]
From a software point of view a 16505A comes with HP-UX version 9.03 or 9.05 and the special logic analyzer application preinstalled. While it is possible that a "re-ignite" CD-ROM did exist for the 16505A, I have never seen one myself, nor have ever I seen anyone else claim that they had one or that they had seen one.
I do have a 16505A A.01.40 software update CD-ROM which I got directly from HP / Agilent years ago when it was available on request. That is not a bootable "re-ignite" CD-ROM, and contains no HP-UX installation files. That CD-ROM is only set up to update an existing 16505A software installation. It contains scripts which are executed by the 16505A software to extract and install new versions of the 16505A software components from cpio file archives on the CD-ROM.
Quite a while ago I tried installing HP-UX 9.05 from scratch on a 712, and then tried to manually execute some of the installation scripts on the 16505A A.01.40 software update CD-ROM. Comparing the results from doing that with the files installed on a working 16505A it appeared that most of the necessary logic analyzer application files were installed, but maybe some shared libraries or other files were missing and weren't installed from the standard HP-UX 9.05 installation nor from the 16505A A.01.40 software update CD-ROM archive files. I never made a complete list of what files might be missing, and if a working 16505A clean install could be created that way by tracking down a small set of missing files and copying them over. It would be interesting to revisit and complete that exercise some day if I ever get motivated again to do that.