AW: C64 Keyboard Scanning

From: Spiro Trikaliotis (Spiro.Trikaliotis_at_gmx.de)
Date: 2000-10-10 15:22:42

Hello Nicholas,

> [COPLIN, Nicholas.]  So the feedback scheme is possible, but
> would require
> four-bit logic?

Well, yes, I believe this should work.

> btw, do I have it correct in that normally port A does the
> driving, port B
> is read? Is there any *danger* if with interrupts disabled I
> reverse this
> (first making both inputs).

No, this shouldn't be a problem at all (but some emulators might have
problems with this).

Well, remember even the fact that when moving the joystick, a GND is
connected to an output (CIA port A!).

Mit freundlichen Grüssen,
   Spiro Trikaliotis.

--
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Spiro R. Trikaliotis            Otto-von-Guericke-Universitaet Magdeburg
Phone: +49 (0)391 67-12560                     Fakultaet fuer Informatik
Fax:   +49 (0)391 67-11161               Institut fuer verteilte Systeme
EMail: spiro@ivs.cs.uni-magdeburg.de   Echtzeitsysteme und Kommunikation
http://ivs.cs.uni-magdeburg.de/EuK/             PF 4120, 39016 Magdeburg
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