Actually, in some respects it was that book that made my reputation, not vise versa. I wrote it when I was just getting into second gear writing technical articles in the magazines. I was introduced to a book acquisitions editor at Scott, Foresman by my editor at PC Tech Journal in 1983, and he took my proposal on her recommendation.
Turbo Pascal's low price compared to most other compilers made it an impulse buy. $50? Why not? And word-of-mouth did a lot of the rest.