Dear Richard, I have an HP 4952A that I am trying to coax back into life. It would be very useful to have the software that you have mentioned as alas the disks have disappeared. A point that may interest you is a note in the operating manual (at least it was still there), section 12-21 concerning the copying of disks. {Note: Some software applications are not reproducible. The will appear to be copied, but will be non-executeable. When you try to load this type of application, the HP4952A will display the error message 'Application Denied'.} This seems to explain the problem that you encountered. Anyway I would like to have a go at persuading the the analyser to accept these files. It may be possible to open up these files and "hand input" them into the analyser and then save them to disk for later use. As the saying goes: "Nothing ventured, nothing gained". Regards, Rupert.