Budd's introduction to Smalltalk programming and the Little Smalltalk interpreter focuses on elementary, rather than advanced topics of object-oriented programming. The Little Smalltalk system runs under the UNIX operating system and can be executed on conventional terminals.
An easy to digest introduction to (a dialect of) Smalltalk. While a bit outdated, it is recommendable if you want a quick intro to the essentials of the language.
Of especial interest is the second part of the book, where the author gives a nice sketch of the Little Smalltalk implementation: object representation, memory management and evaluation strategies. While not complete, it is nicely written and gives enough detail to understand the actual implementation.