An idea: emulating dirty pin connector?

Discuss emulation of the Nintendo Entertainment System and Famicom.

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mkwong98
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An idea: emulating dirty pin connector?

Post by mkwong98 » Tue Feb 18, 2020 7:42 pm

Having some graphic glitches due to dirty pin connection is part of my childhood memory, so I think it would be fun to have an option to emulate this. How would you implement this? How dirty or which pin can get dirty and yet the game is still playable? And what other HW defects can you think of?

lidnariq
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Re: An idea: emulating dirty pin connector?

Post by lidnariq » Tue Feb 18, 2020 8:07 pm

CHR lines are more-or-less safe to corrupt. PRG lines are mostly not.

The easiest to describe would be to randomly switch CHR and nametables between open bus and correct. In practice, this means that random slivers will be of some portion of the "open bus" picture, because a temporarily missing nametable or pattern table will try to render the lower 8 bits of the address bus as data.

Drag
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Re: An idea: emulating dirty pin connector?

Post by Drag » Tue Feb 18, 2020 9:00 pm

It's funny this thread comes up, because I was thinking about how 8-bit creepypasta games tend to make text or graphics on the screen flicker, but usually between wrong tiles or creepy messages for just one frame, and I don't remember the last time I saw someone try to do something like what happens on the NES when the CHR lines are dirty, which is often fun in how it has a "creeping up" effect which can come and go. :P

So yeah, I'd be interested in seeing something like this too.

lidnariq
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Re: An idea: emulating dirty pin connector?

Post by lidnariq » Wed Feb 19, 2020 12:55 am

mkwong98 wrote:
Tue Feb 18, 2020 7:42 pm
And what other HW defects can you think of?
Emulate CIC negotiation failure with 50% odds each time someone opens a file :P

calima
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Re: An idea: emulating dirty pin connector?

Post by calima » Wed Feb 19, 2020 2:25 am

Only the best emulators include a "blow on the cart" option.

pwnskar
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Re: An idea: emulating dirty pin connector?

Post by pwnskar » Wed Feb 19, 2020 6:57 am

I think a feature like this could be useful as a cross reference when testing on real hardware.

I personally have some weird sprite issues when running my project on one of my machines. Being able to emulate various hardware failures would be a nice tool to track down where things are going wrong.

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NovaSquirrel
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Re: An idea: emulating dirty pin connector?

Post by NovaSquirrel » Mon Feb 24, 2020 10:05 pm

I've seen videos of people showing off their mysterious "glitchy" cartridges before, where someone with NES development knowledge would know that they just happened to be the interrupt request pin not making contact. I've explored how that looks a bit with a modified MMC3 PowerPak mapper that had interrupts disabled, and just disabling interrupts is an even easier thing to emulate than CHR pin stuff.

unregistered
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Re: An idea: emulating dirty pin connector?

Post by unregistered » Mon Mar 02, 2020 4:43 pm

calima wrote:
Wed Feb 19, 2020 2:25 am
Only the best emulators include a "blow on the cart" option.
:lol: :shock: Have never stumbled across that best emulator option in Mesen... Sour, this is disappointing :wink:

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