Rapid Fire Zapper

[glassjester]

Is it possible to allow rapid/automatic fire in Zapper games, by holding down the trigger?

To my knowledge, none of the NES Zapper games have this feature, but could that be changed by altering the rom?

Or better yet, via Game Genie?

[Disch]

Zapper works by detecting light.  It knows you hit something because for a single frame, the entire screen is black except for the target, which is white.

For a rapid-fire to work, it'd have to constantly be flashing the screen nonstop -- to the point of it being intolerable and/or seizure inducing.

So no, this cannot be done practically.

[glassjester]

Space Shadow did it.

Besides, games like Operation Wolf and To The Earth require you to pull the trigger over and over, in quick succession. The screen is constantly flashing in those games. Yet they're still very playable.

Would it be possible to create the same effect by just holding down the trigger?

[Disch]

Hrm... maybe I was a bit overzealous?   

Space Shadow doesn't appear to flash the whole screen, but only flashes the target.  Which I guess would work as long as nothing else on the screen is moving.

As for holding the trigger, holding at full pull wouldn't work due to the way the zapper works.  If you have one, pull it out and follow along with the below:

The trigger has 3 states:
A) Not pulled
B) "pulled"
C) "full pull"

Pull the trigger very slowly, and you'll feel/hear it transition between these states.  The A-B transition is very subtle, and has a very soft "click" that most people don't notice.
The B-C transition is the extremely loud and noticable "CLANG" that everyone thinks of when they think of the zapper trigger.

The problem is, even though the trigger has 3 states, the zapper only returns 2 to the NES.  It gives a '1' if the trigger is in state B, but gives a '0' if the trigger is in state A or C.  So there is no way for the game to know whether or not the trigger is being held down fully, or is not being held at all.  Most games look at the 1->0 transition ("CLANG") to see when the trigger as pulled.


You could keep the trigger in state B and do a rapid-fire that way, but it would be awkward, as you'd have to be holding the trigger in a somewhat narrow spot between the click and CLANG.  So theoretically possible I suppose, but it'd be weird.

[Jorpho]

Neat!  The white-square story gets tossed around often enough, but I didn't know about this transition thing.

Sounds to me like you could program the game to detect the transition, and subsequently simulate the transition repeatedly until the transition is actually detected again (i.e. when the trigger is released).  It doesn't sound easy, though.

[Disch]

Sounds to me like you could program the game to detect the transition, and subsequently simulate the transition repeatedly until the transition is actually detected again (i.e. when the trigger is released).  It doesn't sound easy, though.

It doesn't transition on release, though.  It goes straight from C->A.. reporting a 0 state throughout.  The 'CLANG' is effectively the trigger release (not the trigger pull, even though it happens when you pull the trigger).  And to get any differing state to report, you have to release the trigger and pull it again.

Zapper was not designed with rapid fire in mind.

[KingMike]

none of the NES Zapper games have this feature,

How much do you like having all your fingers?
(a real Zapper has some kind of spring, I assume, in the trigger to physically prevent it from being pushed rapid-fire)

[glassjester]

How much do you like having all your fingers?

Very much!

Which is why I'd love if someone knew a way to get the Zapper to rapid-fire. Have you played "To The Earth" ? It's  a real trigger-pulling endurance test.

It's the Activision Decathlon of Zapper games.

[ETG]

You'd probably be better off hacking the hardware of the zapper. Maybe a 555 circuit behind the trigger and a pot to control the timing.

But my experience with electronic hardware has been exclusively replacing burnt components with less burnt ones, so it may not be as simple as I assume it would be.

[Jorpho]

It doesn't transition on release, though.  It goes straight from C->A.. reporting a 0 state throughout.  The 'CLANG' is effectively the trigger release (not the trigger pull, even though it happens when you pull the trigger).  And to get any differing state to report, you have to release the trigger and pull it again.

Well, is it possible to read data from the zapper without touching the zapper's trigger at all?  Then it might be possible to program the game to go into "rapid fire state" by, say, pushing the Select button on the controller.

[Disch]

Well, sure, but it wouldn't really feel natural if you're not holding the trigger.  It'd make more sense to have the trigger toggle rapid-fire state rather than the select button.  But even that would be weird.


But whatever -- that's all my personal preference.  Yes, what you are asking could definitely be done.