First cartridge prototype questions

Discuss hardware-related topics, such as development cartridges, CopyNES, PowerPak, EPROMs, or whatever.

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ninja_kun
Posts: 13
Joined: Fri Jun 17, 2022 5:02 am

First cartridge prototype questions

Post by ninja_kun »

Hi all.

I'm prototyping a Famicom cartridge using a flash chip for PRG in a ZIF socket, and jump wires into IDC headers. A few basic questions please (I'm new to electronics, so apologies for the basic questions).

1. The flash chip has 2 unused address lines. Can I just tie unused inputs on the flash chip to ground? Do I need to do that through a resistor or just a wire?
2. Same question for the active-low write-enable line, except that it will be tied to 5V. Resistor needed?
3. Is it ok to have nothing connected to the PPU lines at all to start with? I understand that the PPU will read garbage, but is that a problem if I don't connect a display? Or should I at least tie the PPU data lines to ground?
4. Any other gotchas I should be aware of before I power on with my franken-cartridge inserted? :)

Thank you!
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: First cartridge prototype questions

Post by lidnariq »

ninja_kun wrote: Tue Jul 05, 2022 9:05 pm 1. The flash chip has 2 unused address lines. Can I just tie unused inputs on the flash chip to ground? Do I need to do that through a resistor or just a wire?
Yes, and a wire is fine.
2. Same question for the active-low write-enable line, except that it will be tied to 5V. Resistor needed?
Yes, and no resistor is needed.
3. Is it ok to have nothing connected to the PPU lines at all to start with? I understand that the PPU will read garbage, but is that a problem if I don't connect a display? Or should I at least tie the PPU data lines to ground?
Yes, the PPU data lines can float. Do not tie the data lines to anything - on a normal NES those pins are used for both address and data. (Later famiclones didn't need to save pins by combining both address and data on the same physical pins, and got rid of this behavior)
ninja_kun
Posts: 13
Joined: Fri Jun 17, 2022 5:02 am

Re: First cartridge prototype questions

Post by ninja_kun »

Thank you so much! It worked first time!! :shock:

I spent a few hours wiring it and checking with a multimeter last night, your answer gave me the courage to power it on :beer:
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