Actually, "Oh, Pascal" is mentioned in the Readme with the interpreter. Funny thing is it says it's not to be redistributed and that it's only for that book.

And yeah, I already got a free copy of THINK Pascal. I just wanted to have a copy of the interpreter mentioned in the book, because I was curious to see what the development environment was like back when the book was made. I tried it out and it works in Mac OS 9.

I keep reading about this "MacPascal" but haven't been able to find a copy of it.... If anyone happens to know where a copy is I'd appreciate it.