Re: [stella] Thinking... [nearly ot]

Subject: Re: [stella] Thinking... [nearly ot]
From: Tennessee Carmel-Veilleux <veilleux@xxxxxxxxx>
Date: Thu, 27 May 1999 16:33:08 -0400 (EDT)

On Thu, 27 May 1999, John K. Harvey wrote:

> The whole screen in Duck Hunt (at least the blue background) flashes for a
> frame, and then the white boxes appear around the ducks for a frame or two.
> 
> Figured I'd hook it up for a few minutes.  Everyone's gotta love shooting
> virtual ducks. :)
> 
Well since I'm MUCH better at NES programming than 2600, I'll easily answer
this one...

The Zapper works by using the 2 "unused by joypad" bits of the controller
port (D3/D4). When you press the trigger, the game detects it and goes to
"turning off" the background and changing the pattern of the sprite to a
white square. Then some timing is needed because the "white" flashes at
15khz. The software reads the digital amplified signal from the
phototransistor and if you get white and it oscillates at the right
frequency, a hit is registered.

	Regards,

--
Tennessee Carmel-Veilleux (Coordonator of Digital Meltdown)
veilleux@xxxxxxxxx (www.ameth.org/~veilleux) ICQ ID : 8604827
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||*|| This message was written in Canada / Ce message a ete ecrit au Canada




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