Turbo Pascal 5.5 Object Oriented Programming Guide -

Larry Tesler’s work for the Macintosh.

Flexibility in how memory was handled.

Allowing for polymorphism where child objects could redefine behavior. Turbo Pascal 5.5 Object Oriented Programming Guide

Borland didn't invent these concepts from scratch. The OOP extensions were heavily inspired by: Larry Tesler’s work for the Macintosh

Influencing the "native code" approach rather than an interpreted one. Key Innovations in 5.5 included: Turbo Pascal 5.5 Object Oriented Programming Guide