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From: lee@rocksanne.uucp (Lee Moore)
Newsgroups: comp.graphics
Subject: Re: More on the Patent question....
Keywords: Cadtrak patent XOR split-screen
Message-ID: <454@spot.wbst128.xerox.com>
Date: 18 Jul 90 20:14:36 GMT
References: <646@dg.dg.com>
Sender: news@spot.wbst128.xerox.com
Reply-To: moore.wbst128@xerox.com (Lee Moore)
Organization: Xerox Webster Research Center, Webster, NY, USA
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RE: Cadtrak patent

The Xerox Alto computer had what were called display control blocks (DCBs).  
The display controller would go thorough a linked list of blocks of bitmaps
and display them sequentially.  The first bitmap block would be at the top,
the second right below it, and so on.  The first Alto was created in 1973.
The history and design of the Alto are described in a report called:
	Alto: A personal computer
	by C.P. Thacker, E.M. McCreight, B.W. Lampson, R.F. Sproull and D.R. Boggs
	Xerox Palo Alto Research Center (PARC) report # CSL-79-11

--

Lee Moore -- Xerox Webster Research Center -- +1 716 422 2496
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