HP 71B Diagnostic ROM

[Raymond Del Tondo]

(12-30-2013 06:53 PM)Dave Frederickson Wrote:  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?

I'm sure the HP-71B with datecode 2515 either has transplanted innards from a later unit, or at least the back side has been replaced.

I have seen HP-71B units from 1987 with ROM 1BBBB, and the update to ROM 2CCCC happened in 1987, and shortly after the first upgrade the ROM 2CDCC was released.