You are correct. In the early days, most Smalltalk products were commercial and entailed expensive licensing fees.

There were a couple of free Smalltalk products like Timothy Budd’s Little Smalltalk (circa 1987) and GNU Smalltalk (1991), but they were hardly ready for commercial use.

Squeak arrived in 1996 but it was mainly for educational and hobbyist use. Juan Vuletich’s Cuis Smalltalk followed shortly and was derived from Squeak, but it never gained much traction.

The first real open source Smalltalk for commercial use was Pharo (2008). It is remarkably innovative and should soon give Cincom Smalltalk a run for its money.

Here are some great learning resources:

This book (not free) is my favourite for learning how to use Smalltalk for object-oriented programming: Smalltalk, Objects, and Design, by Chamond Liu.

I myself have published a whole bunch of Smalltalk tutorials. The latest ones are:

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