Objects belong to classes and each class shares a common set of
messages that they handle.  A class is created by sending a special
message to a special object and then sending the new class
informative messages about itself.

Each class of objects has a list of actions that it does
to answer a message. If the message can't be
answered by an object of one class then there is a specified
'superclass' to which the message is transfered.  

An object has a list of variables that belong to that object
from the time it is created. The answer to a message
can involve both reading and writing these values. The variables
found in each class of objects is determined by the class of the
object so, when a new class of object is defined sets of of hidden
variables are defined.

One of the primitive data types included is Object.  
Each Class is also an object in its
own right and has a separate set of of variables which are accessable
by objects of that class - so for example if we had a class called
BOOKS then the number of BOOKS would be a class variable and each Book's
author would be an 'instance' variable - associated with the objects
not the collection.

Definitions:
	o selector - a symbol used to select an appropriate method
	o message - a selector and a list of actual arguments
	o method - the code that answers a message

Predefined objects

Tiny Smalltalk Is set up with this Class hierarchy
	Object
		Class
		Boolean
			True	true
			False	false
		File
		Block [...]   [...|...]
		Method
		Smalltalk
		Context
		UndefinedObject
		Link
		Switch
		Random
		Symbol   #...
		Magnitude  (ordered objects)
			Number
				Integer  123
				Float	 12.34
			Char $...
			Collection
				List
					Set
				Interval
				IndexedCollection
					Dictionary
					Array	#(...)
						ByteArray #[...]
							String '...'

This can be modified and extended and the result saved.  The hierarchy
can then be reloaded at the start of the next session.

The initial setup is described - in Smalltalk in
	~dick/cs320/smalltalk/basic.st 
and
	~dick/cs320/smalltalk/unix.st