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From: johnson@cs.uiuc.EDU (Ralph Johnson)
Newsgroups: comp.lang.smalltalk
Subject: Re: novice question about Smalltalk books
Message-ID: <1991Mar14.231825.21901@m.cs.uiuc.edu>
Date: 14 Mar 91 23:18:25 GMT
References: <27324@netcom.COM> <3764.27dcdeca@iccgcc.decnet.ab.com>
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Reply-To: johnson@cs.uiuc.EDU (Ralph Johnson)
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In article <3764.27dcdeca@iccgcc.decnet.ab.com>, klimas@iccgcc.decnet.ab.com writes:
In explanation of why the Blue Book got replaced by the purple book,
which omits the section that describes the ST-80 virtual machine:

|> 	The two most plausible answers are 
|> 		1.)The current virtual machine in ST-80/Arrival is dramatically
|> 		different than was described in the Blue Book and hence the
|> 		information was obsolete.
|> 
|> 		2.)There was too much information on how to build virtual
|> 		machines and ParcPlace was concerned about even more
|> 		competitors.

The description in the Blue Book on how to build a virtual machine
was never accurate.  Nobody ever built them that way.  Well, at least
nobody who got a useable implementation on a nonmicrocoded machine
built them that way.  It was useful as an operational specification
of Smalltalk, not as a description of how the implementation worked.

The Blue Book description is still useful to get the "big picture" of
how Smalltalk works, but it is no longer an accurate specification of
the virtual machine, let alone a description of of its implementation.

The best description of how Smalltalk is implemented is in the 1983
Symposium on Principles of Programming Languages conference proceedings
and is by Peter Deutsch and Alan Schiffman.

Ralph Johnson -- University of Illinois at Urbana-Champaign