Re: [stella] 6532 port A input only?

Subject: Re: [stella] 6532 port A input only?
From: "Eckhard Stolberg" <Eckhard_Stolberg@xxxxxx>
Date: Thu, 22 Apr 2004 23:42:47 +0200
> The keyboard controllers do.  They are constucted as an x-y grid.
> The 4 RIOT lines are connected to x[3:0].  The trigger input and the
> 2 paddle inputs are connected to y[2:0].
> I believe the paddles operate in a similar way.  Set the necessary outputs
> to 1, then read the paddle inputs.
> Kirk you've done this recently, do I have it right?

You are right about the keyboard controllers. But the paddles don't
set the RIOT to output. They only ground the capacitors for a moment.
This is done through a bit in the VBLANK register.

The Kid Vid controller does output through the controller port
to pause the tape though. Also the Mindlink controller get's
told to send new data this way. And the Compumate keyboard
even does the bankswitching for it's cartridge though the
joystick port.

Star Raiders also sets all 8 pins to output. This is because
it uses a keyboard controller. But it also sets the pins for the
joystick to output. It still is able to read the joystick
directions because it sets the corresponding pins to 1. When
a directions is pressed, it connects this pin to ground, which
seems to be the same thing that happens when you output a 0
on it.

Ciao, Eckhard Stolberg

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