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From: jc@sdcsvax.UUCP (John Cornelius)
Newsgroups: net.info-terms
Subject: Re: Wyse "magic cookies"
Message-ID: <1374@sdcsvax.UUCP>
Date: Mon, 3-Feb-86 11:16:31 EST
Article-I.D.: sdcsvax.1374
Posted: Mon Feb  3 11:16:31 1986
Date-Received: Wed, 5-Feb-86 01:51:45 EST
References: <312@uw-june> <120@ucdavis.UUCP>
Reply-To: jc@sdcsvax.UUCP (John Cornelius)
Distribution: net
Organization: Western Scientific, San Diego
Lines: 22
Keywords: Cheap glitz
Summary: First Class is worth it!

The reason terminals have magic cookies is because the internal character size
is insufficient to hold data about video attributes. Terminals without magic
cookies typically have 4 or 5 extra bits in the internal character
representation. Each bit indicates the state of 1 video attribute for that
character only. Terminals with magic cookies may have 1 bit which indicates
that the current character sets video attributes and the character contents
itself gives the video attributes. Video attributes remain effective until
another such character is encountered. Since there is a 1:1 mapping of data
bytes (in memory) to screen position the effect of a backspace following a set
attribute command is often described by the manufacturer as unknown.

Magic cookies allow the manufacturer to hype a large number of video attributes
and make his terminal look glitzy while keeping the terminal cheap to design
and manufacture. The manufacturing cost savings are enormous, about $10.00,
when compared to the total manufacturing cost of the terminal, about $140.00 to
$200 for most ascii terminals. A true VT-200 emulating ANSII terminal (no magic
cookie) costs $180.00 POE West Coast to bring to market. An ADM-3 look alike
costs about $140.00 to bring to market under the same conditions. The $40.00
difference means about $120.00 by the time it gets to the end user.

John Cornelius
Western Scientific