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From: ken@turtlevax.UUCP (Ken Turkowski)
Newsgroups: net.arch
Subject: Re: Arbitrary byte alignment
Message-ID: <558@turtlevax.UUCP>
Date: Sun, 14-Oct-84 21:00:42 EDT
Article-I.D.: turtleva.558
Posted: Sun Oct 14 21:00:42 1984
Date-Received: Tue, 16-Oct-84 05:29:24 EDT
References: <426@ima.UUCP> <3637@ut-sally.UUCP>
Organization: CADLINC, Inc. @ Palo Alto, CA
Lines: 21

> There is in fact a rather obvious solution to the alignment/performance
> issue (I cannot bring myself to call it a problem) which satisfies
> everyone except the members of a group I shall refer to as X.
> Assuming eight-bit bytes and 32-bit words, the method involves four
> independent byte-wide* memories (two LSBs for bank select), a
> +0:+1:+2:+3 circuit, and eight 4-by-4 crossbar switches.  The exact
> details of implementation, the reasons for its unpopularity, and the
> identity of X are left as rather trivial exercises for the reader.

An extension of this technique is used in high-performance raster
graphics systems, which allows access to several horizontally-,
vertically-, or block-contiguous pixels.  It is called a tesselated
frame buffer, and is described in two recent papers, one about a year
ago in IEEE Computer Graphics and Applications, the other in this
years' SIGGRAPH tutorial on State-of-the-Art in Image Synthesis.  If
there is any interest, I can dig up the exact references and post them
to the net.
-- 
Ken Turkowski @ CADLINC, Palo Alto, CA
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