If you are interested in looking more closely at Smalltalk 72, there's a manual available: http://www.textfiles.com/bitsavers/pdf/xerox/alto/Smalltalk7...

I'd recommend checking it out, it's quite different from Smalltalk-76 (which is pretty much "modern" Smalltalk) and has some novel ideas. They may not be good ideas (after all Smalltalk-76 was very different), but they are novel!