Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!evax!cs4344af
From: cs4344af@evax.arl.utexas.edu (Fuzzy Fox)
Newsgroups: comp.sys.cbm
Subject: Re: Mouse driver for C-128 in 80 column (text mode)
Keywords: mouse driver c128
Message-ID: <1990Nov29.065712.5043@evax.arl.utexas.edu>
Date: 29 Nov 90 06:57:12 GMT
References: <1990Nov28.220618.23036@vlsi.polymtl.ca>
Organization: Computer Science Engineering Univ. of Texas at Arlington
Lines: 20

In article <1990Nov28.220618.23036@vlsi.polymtl.ca> if18@vlsi.polymtl.ca writes:
>>You should use $D600, bit 6 to determine if the video is being
>>refreshed, and when it is, then do your changes to the character info.
>>Not the most efficient way to use CPU time, but it works.
>
>I agree. It's not efficient... but does anybody have another suggestion ?
>Does anybody know how the mouse driver for the Pocket series does it ?
>

Here's a silly idea.  Wait until you see $D600 show that the video
retrace is being done, then note the raster line at $D011/12 that the
VIC is currently drawing.  Since the two of them probably are both
drawing screens at exactly 60 Hz, if you set a raster interrupt on the
VIC at that line, it will probably trigger just when the VDC is doing
its video retrace, so no checking would be needed.

The above would be an initialization procedure, and once set, no need to
examine $D600 again.

					A bizarre fuzzy mind.