Personal computer? There were machines that
significantly predated it
that were more capable, and could be considered "personal".
I don't know enough about this particular machine to conclude whether it
was or wasn't a personal computer. But it's fair to reason that the
designer, in talking to you, specifically meant personal "desktop" computer.
Was the P101 the first personal computer? My opinion
is that it isn't,
but then some might argue. Some consider the Berkeley SIMON computer,
developed in the late 1940s, with articles on how to build the
relay-based machine published in Radio Electronics in the early 1950's,
to be the first personal computer.
Again, I'm not (yet) taking a stand either way, but if the P101 was
fully electronic, vs. your earlier examples which aren't, then that's
another qualifier: it stands to reason that the designer meant "personal
desktop-sized fully electronic computer."
To be clear: do you not consider the P101 a "computer" at all? If so,
then what's your distinction between "calculator" and "computer"
when
the 101 has conditional branching?