Re: [cc65] Question on 1351 mouse

From: Ullrich von Bassewitz <>
Date: 2010-02-01 19:20:40
On Sat, Jan 30, 2010 at 07:40:37PM -0500, Greg King wrote:
> Some of that cross-talk can be avoided by the mouse driver.  The driver
> can change the values in the keyboard matrix's output port and direction
> registers during it's reading of the buttons.  I did that in a driver that
> I created decades ago for the ROM Kernal's screen editor.  It translated
> mouse movement into cursor characters.  The blinking text cursor followed
> the mouse's I-beam sprite around the screen.

Isn't there a similar problem with the joystick (at least one of them): Moving
it generates phantom characters. As far as I remember, the mouse buttons are
connected to some input lines also used by the keyboard matrix. If this is so,
and if the kernal keyboard scanning routine programs the I/O chip, then
there's not much the driver can do. Every change to the output direction
register will be undone by the kernal. Maybe I'm wrong ... Anyway, I would be
curious to see that code.



Ullrich von Bassewitz                        
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Received on Mon Feb 1 19:20:48 2010

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