SN74LVC1G57DBVR settled truth-table and strap experiment

Use the English article for the fixture, limits and power-off procedures.
The worksheet has 8 independent-input rows and 4 rows for each physical
strap. Work on a copy of observations-blank.csv. Record only settled
bench voltages you measured, with the Fluke or equivalent meter COM
connected to the same fixture ground.

  python3 truth_table.py observations.csv
  python3 -m unittest -v test_truth_table.py

Exit 0 means all 16 rows matched. Exit 1 flags rail, input or output
readings. Exit 2 reports a malformed or incomplete worksheet.
Host tests use constructed readings. No physical measurements,
firmware build or target execution is claimed by this package.

fixture.svg is the original editable diagram. fixture.png is its
full-size 1600 by 960 companion. Read the chip from its documented
DBV top view. Other package variants are outside this fixture.
