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From: drp@buhub.bradley.edu (Douglas Pokorny)
Subject: Re: MS-Mouse driver version 7.04
Message-ID: <1991Apr4.231414.7598@bradley.bradley.edu>
Keywords: mouse driver
Sender: news@bradley.bradley.edu
Nntp-Posting-Host: buhub.bradley.edu
Organization: Bradley University
References: <25180@hydra.gatech.EDU> <1991Apr02.214112.6722@groucho>
Date: Thu, 4 Apr 91 23:14:14 GMT
Lines: 28

edvs@ted.cs.uidaho.edu writes:

>   Norton's Utilities 5.0 uses graphics mode, not text mode, which is why it
>has a smooth cursor.


Actually this is not true.  Norton 5.0 does use text mode, however it 
uses the reprogrammable character generator of the EGA and VGA cards
to produce the buttons, click-boxes and mouse pointer.  Everytime
the mouse is moved the software reprograms the pointer.

Basically it works like this:  the characters currently on the screen
are read and duplicated in spare "dummy characters" the mouse cursor
is overlayed upon them and they replace the characters currently at
the mouse position.  Using this scheme, Norton has to have at least four
"dummy" characters, because at any one time their cursor can be on
four characters.

You can tell that the cursor is emulated in text mode because if
you watch it move horizontally, you'll notice that a band of
distorted pixels will travel the length of the cursor.  This is a 
clear sign that the screen is in 720x400 text mode, and the 9th
pixel in each character box is a duplicate of that in the eigth.
(This duplication only occures with about 32 characters in the
upper 128 of the character set)

-Doug
drp@buhub.bradley.edu