3rd chip inside the Super Mario Bros Cart?

[electro]

Hi,

I bought the smb, opened it up and see the PRG and CHR chips, but also a smaller chip on the side which says 3193A 1986

I wasn't expecting to see a 3rd chip. The PCB has "NES-NROM-256-02"

What is the 3rd chip for?

Also I see what I believe is an RC timer (resistor/capacitor) for the chips? Has anyone ever messed around with that?

Thanks,
T

[kyuusaku]

The third chip is the "CIC" lockout chip. There shouldn't be an RC oscillator (this what you mean by timer?), you are probably looking at two capacitors, just one of them is in a resistor-like package.

[tepples]

What is the 3rd chip for?

To put it briefly, this chip embodies Nintendo's anti-competitive practices.

[electro]

The same chip is also inside the NES on the main board.

If using my own PRG rom chip inside the smb cart would the cic chip in the cart cause a problem?

I disabled the cic chip on the main board by cutting pin 4.

T

[electro]

The third chip is the "CIC" lockout chip. There shouldn't be an RC oscillator (this what you mean by timer?), you are probably looking at two capacitors, just one of them is in a resistor-like package.

On one side of the board (chip side) there is a small cap, the directly under that on the other side of the board wired in parallel is a resistor.

I thought maybe that was providing the clock for one of the chips.

Thanks,
T

[BMF54123]

If you've disabled the CIC in the console, then you shouldn't have anything to worry about.

[electro]

Ok, thank you.

I saw this tutorial onthe web where this guys was showing how to disable the cic chip inside the NES, rather than the cart.

I always thought that chip was in the NES system, I didn't expect to see the same chip inside the cart too.

I wonder why it's in the NES and in the cart?

Tony

[MottZilla]

In the NES, it is wired differently to run in something like "Lock Mode". The one in the cartridge runs in "Key Mode". If your cartridge doesn't have the chip running as a key, your chip in the NES running in Lock Mode will keep reseting the system to prevent you from playing unlicensed software.

If you modify your NES to make the chip inside it run in "Key Mode" then you don't even need a chip in your cartridges anymore as it won't reset the system anymore as it isn't in lock mode.