HP-71B HHP EPROM PCBs

[J-F Garnier]

Basically, I only see two versions: the 1984 and 1986 versions.
The four lower units are basically the same, differing only by manufacturing details.
The part that looks like a resistor is actually an inductor (labelled as 'L01' on the 1986 version) for unknown use, maybe filtering. This inductor is present on all versions but can have several form factors, so the differences on various production batches depending on component sourcing.

Still I would be interested by the documentation of the HP interface chip (1LJ4), maybe will it be released someday thanks to the recent documentation effort.
I always though it could be possible to modify the 32K EPROM module to a 64K version, but would need that documentation.
32K is too small, with 64K it could be possible to put JPCROM + MATH, possibly plus ULIB52 (Forth ROM is not possible).

J-F