Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!usc!snorkelwacker.mit.edu!bloom-beacon!mcgill-vision!thunder.mcrcim.mcgill.edu!poly-vlsi!if18
From: if18@vlsi.polymtl.ca
Newsgroups: comp.sys.cbm
Subject: Mouse driver for C-128 in 80 column (text mode)
Keywords: mouse driver c128
Message-ID: <1990Nov28.220618.23036@vlsi.polymtl.ca>
Date: 28 Nov 90 22:06:18 GMT
Sender: if18@info.polymtl.ca
Organization: Ecole Polytechnique de Montreal
Lines: 57

I posted a message about a mouse driver for the C-128 in 80 columns (text mode)
 a while back... Here it is again:

>Some time ago, I programmed a text mouse driver for the C-128...
>The idea is simple... Everytime the mouse moves, I redefine four
>characters in the VDC (in 80 columns, of course!) and print them on
>the screen where the mouse should be.
>
>The result is a mouse indicator that works very much like the one
>found in programs like the Pocket series (Writer, Planner,...).
>
>Most of the time, the indicator on the screen moves around smoothly.
>However, from time to time, the indicator flashes as it's moving.
>It seems to be happening whenever the raster beam passes over it (I can
>actually keep it flashing if I follow the raster beam at constant speed).
>
>My question is:
>
>Is there any way to avoid the unpleasant flashing ?
>
>In 40 columns, this problem could be solved by generating a interrupt
>with the raster beam (when it's outside the screen). All I'd have to
>do is wait for the interrupt and then redefine the character
>set. Can the same register be used for the 80 column screen ?? (I don't
>think so, but anyone knows for sure ?)
>
>If it can't be used, is there another register for the 80 column ?
>Can I used bit 6 of address $d600 (in read mode) to know if the raster
>beam is outside the screen , or is there an internal VDC register that
>could be used ??
>
>I know it can be done because Pocket Writer and the likes don't have
>this problem.
>
>Any help would be greatly appreciated.
>Thank you.


cs4344af@evax.arl.utexas.edu (Fuzzy Fox) answered:

>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 ?

By the way, for some unknown reason to me, I registered as being 
if18@vlsi.polymtl.ca... This is NOT RIGHT !!!  Please send any mail
to if18@info.polymtl.ca


--


   Miguel Pedro
   Send mail to if18@info.polymtl.ca (NOT @vlsi.polymtl.ca !!!)