nesdev.org

For whatever reason this post pops up once a year in my news on how to "unlock hidden levels" for Super Mario for NES with a top loader and tennis cartridge. I have done it a few times and had success but always feel like I am one step away from frying my NES. What are your guys thoughts on this? Will it damage a system?

http://www.businessinsider.com/secret-l ... own-risk-8

Hot-swapping carts isn't exactly great for the NES, but I don't think you'll break anything from doing so.

I wonder how that happens, AFAIK NES cannot separate a cold boot from warm reset in code.

calima wrote:I wonder how that happens, AFAIK NES cannot separate a cold boot from warm reset in code.

Sure it can, you can check variables in RAM and if it's set it's a reset, if not it's a power-on and then you set that variable. I'm sure several games do that, I haven't played it in years but IIRC Final Fantasy was one, and it would skip the intro when you reset it. When using battery-backed RAM, you pretty much have to do something like this to know whether to initialize the RAM or not.

I'd guess in this case the games were using the same variable to do a similar kind of check and that's causing the weird stuff to happen.

I have actually done this with success. I had these weird (obviously) glitched out levels that were amusing to run through. Honestly though, you can get a similar effect just online searching Game Genie codes that alter the levels as well and no chance of damaging the always pricey top loader system.

Memblers wrote:

calima wrote:I wonder how that happens, AFAIK NES cannot separate a cold boot from warm reset in code.

Sure it can, you can check variables in RAM and if it's set it's a reset, if not it's a power-on and then you set that variable. I'm sure several games do that, I haven't played it in years but IIRC Final Fantasy was one, and it would skip the intro when you reset it. When using battery-backed RAM, you pretty much have to do something like this to know whether to initialize the RAM or not.

I'd guess in this case the games were using the same variable to do a similar kind of check and that's causing the weird stuff to happen.

Yes, SMB and Tennis both try to detect a reset this way, and this trick works because they used an identical check for both games. (In SMB it was intentionally used as a way to continue from the world you were on after reset.)

It's not uncommon for games to try and detect a reset and preserve stuff across reset. My own game does. I think it mostly goes unnoticed because few people would try to reset their game and continue. The Genesis game X-Men was infamous for requiring a reset to complete the game.

By the way, if you have a CopyNES installed, the older versions of its BIOS unfortunately initialize RAM and break this feature of the NES. You can get a newer BIOS to fix the problem though: thread / new BIOS

lidnariq wrote:Hot-swapping carts isn't exactly great for the NES, but I don't think you'll break anything from doing so.

If your NES cartridge has some pins longer/shorter than the others, then that is hotswapping protection. The cartridge chips are a lot less likely to be damaged if the data/address/control/etc signals are disconnected before voltage and ground, which is why the latter pins are longer than the former.

Something like this happened to me with goonies 2, first door warped me to the last door of game. At the time, i was messing around with controllerport, so unplugging and plugging a controller might have a similar effects.

I also remember as a kid to mess around with the controller and get invincibility in Batman.
In The kings of the beach I remember to appear on my opponen's side during the service.
Just letting the ball fall touching the floor scored a point. Very easy to win!!

I remember to have found some other games with these weird controller glitchs, but can't remember wich of them...
Well... that was around 25 years or so... I just can't remember all

Anyway to safely reproduce these glitches??
Maybe if I test with one or more wires disconnected? I think that was what happened that time.

Fisher wrote:Anyway to safely reproduce these glitches??

Emulators are very safe.

A flash cart with a hacked ROM can also do it without hotswapping. There should be a way to Game Genie it as well.

Anyway to safely reproduce these glitches??

With a console, probably not. Standard NES controllers might cause a excessive power drain if plugged incorrectly.
http://en.wikipedia.org/wiki/4000_series