Texas Instruments TI-55-II Scientific Calculator. Programmable!
“With 112 powerful functions for professional engineering, science, and math applications…Use up to 8 memories.“
which should make calculations easier than using ye ol’ slide rule.
I don’t think the quick reference guide below is the Sourcebook, but it does have basic explanations. “Comes with the revised and expanded edition of Calculator Decision-Making Sourcebook that shows how to use all its power.”
Status: The sea monster is growling that this needs to be opened and pulled apart for parts. She is hungry.