HP 71B Diagnostic ROM

[Dave Frederickson]

Thanks everyone for your suggestions. This isn't the first time the topic of memory testing has come up and I've read many of the old posts. I've been intrigued by the Diagnostic ROM since I first learned of it decades ago. The acquisition of a new 71 and memory module seemed like a good opportunity to see if one was available for loan and I am interested in performing a thorough test.
In addition to the Diag ROM, HP also had a "71 Service ROM Hybrid 4-Int", P/N 00071-60908 ($32). Anybody know what this was for?
Speaking of this newly acquired 71, it's the newer version without the flex connecting the PCBs, with date code 2707, yet the ROM version is 1BBBB. There's a 2CDCC on EBay with a date code of 2515. Why does this newer 71 have older firmware?

Dave