Path: utzoo!attcan!uunet!cs.utexas.edu!yale!quasi-eli!cs.yale.edu!zenith-steven
From: zenith-steven@cs.yale.edu (Steven Ericsson Zenith)
Newsgroups: comp.lang.misc
Subject: Re: Query
Message-ID: <1990Aug15.113729@cs.yale.edu>
Date: 15 Aug 90 15:37:29 GMT
References: <5754@uwm.edu> <126800007@.Prime.COM>
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Reply-To: zenith-steven@cs.yale.edu (Steven Ericsson Zenith)
Organization: Yale University Computer Science Dept., New Haven, CT 06520-2158
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In article <126800007@.Prime.COM>, EAF@.Prime.COM writes:
|> 
|> It depends on the way in which your computer buffers data.  Many computers
|> double buffer data.  That is they read it in as disk blocks and keep it
|> in main memory.  When you ask for the next sentence, they get it from the
|> block of memory which contains the whole disk block, avoiding I/O.

What you describe here isn't "double buffering", it's just plain old
"buffering". "Double buffering", as I understand it, enables data to 
be read and written concurrently - that is, whilst one buffer is being
read another can be filled. Useful if you want to keep your DMA engines
busy. Thus far from avoiding I/O it allows computation and I/O to overlap. 

--
Steven Ericsson Zenith              *            email: zenith@cs.yale.edu
Fax: (203) 466 2768                 |            voice: (203) 432 1278
"The tower should warn the people not to believe in it." - P.D.Ouspensky
Yale University Dept of Computer Science 51 Prospect St New Haven CT 06520 USA