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From: martin@uhccux.UUCP
Newsgroups: comp.sources.d
Subject: Lions vs Bach texts (Was Re: Lions book)
Message-ID: <413@uhccux.UUCP>
Date: Sat, 4-Apr-87 03:37:39 EST
Article-I.D.: uhccux.413
Posted: Sat Apr  4 03:37:39 1987
Date-Received: Sun, 5-Apr-87 10:42:31 EST
References: <483@gouldsd.UUCP> <804@aw.sei.cmu.edu.sei.cmu.edu>
Reply-To: medix!martin@uhccux.UUCP (Brian K. Martin)
Organization: U. of Hawaii School of Medicine
Lines: 48
Keywords: uucp AT&T Lions

In article <3852@amd.UUCP> phil@amd.UUCP (Phil Ngai) writes:
>In article <18114@ucbvax.BERKELEY.EDU> schoet@ernie.Berkeley.EDU.UUCP (Steve Schoettler) writes:
>>
>>  Supposing one's site did have source licenses and one had signed
>>non-disclosure agreements, how would one get ahold of this book?
>
>Would someone who has seen both the Lions book and the Bach book care
>to comment on whether there is any reason to bother getting the former
>now that the latter is available? 
>

I just started reading the group.  Are you discussing the two John Lions
booklets on the UNIX Level six source code published back in 1977 or so vs.
the 1986 Maurice Bach book on the design UNIX OS?

If so, the Bach book is both better written and much more complete than the
Lions booklets.  Basically, the Lions booklets comprise a well-annotated
source code listing of an old version of UNIX; the target machine was the
PDP 11/40.  One booklet was a complete listing of the UNIX source code,
including the assembler code for the 11/40.  The accompanying booklet
explained the source code, defined the variables used, etc.

The intention of the booklets was to provide CS students learning about
operating systems with an actual case study.  They really weren't meant for
self-study, as the annotations simply explained how the code worked.  You still
needed someone to tell you about the various operating system concepts including
process control and scheduling, file and memory management strategies, buffers,
I/O, etc.  On the other hand, the Bach book does a good job of explaining what
goes into the design of an operating system, using UNIX as a case study.

Finally, sockets, semaphores etc. weren't implemented back in 1977, when the
Lions books were written.  And 32-bit machines are commonplace now, where the
Lions books dealt with a more limited architecture (remember separate I & D
space?).

In summary, the Bach book is a much better buy, and you needn't go through
the legal hassles of non-disclosure in order to own a copy.  The Lions book
is very out of date, but is an excellent example of how software ought to
be documented.  But I wouldn't waste the time and energy and money necessary
to get a copy.

FYI--I no longer have a copy of the Lions books.


Brian K. Martin, M.D.

ARPA: uhccux!medix!martin@nosc.ARPA
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