It's a miracle this even exists.
The experience of resurrecting this software is similar to the odyssey of Mason Mark, detailed here.
Feel free to look at the code, try to run it and have fun.
Go ahead and open issues - I won't be fixing any of them. Seriously, it's 25 years since I've looked at the source. I have no idea how to get the Newton Toolkit running - you'll need that to compile it.
There are a number of documents with no extension. These are probably in WordPerfect format.
NS BASIC for Newton was released in 1993 and was developed until 1998 when the Newton was cancelled.