nesdev.org

Ok, I pretty much understand how to do this after researching, but I'd just like to confirm this information with the veterans here.

I understand that Mother can be reproduced using TK-Rom boards, but I'm just plain unwilling to give up my copy of Deja Vu.
As I understand it, a TN-ROM is suitable except for the lack of a battery to power the WRAM when the system is off.

What I have is a copy of Tetris 2 I'm willing to offer up as a sacrifice, and a ready supply of diodes, capacitors, resistors, and batteries.

After doing some research and tracing the paths from my copy of Deja Vu, here's what I've come up with: Is this how it is supposed to work?
I understand the concept and what each part does (diodes block system 5v from exploding the battery, or making the battery power the cart, capacitor smooths the transition between system power and battery, and resistors act as voltage magnets).

from what I can see on my copy of Tetris 2, Wram pin 1 has no connection (maybe I can have battery in on pin 1 and leave system voltage on 28 without clipping pins?), and there is already a 2.2uf capacitor on board to the left of the MMC3C (negative connects to ground, positive to 5v).

Can I simplify this by using parts already on the board?

so, no advice on this?

DNSDies wrote:so, no advice on this?

If you look around you'll notice we're not here to help you make repros for numerous reasons.

right, except for the fact this isn't really a repro, since Mother was never released in America.

If I wanted to make money, I'd be using donor boards that didn't require $5 in parts.

This is just for me, I have no intent of selling it.

You don't seem to have any problem with other reproductions on this board.
I can see at least 5 threads on page 1.

These threads just get old. If you're looking for help on a schematic your best bet is to draw it up for yourself and post it asking for feedback. People continually pop in and ask "How do I make a copy of X game for X reason?"

Your basically asking someone to explain the entire process for you. I don't know how to answer your question other than do all the reasearch myself on the differences between the two boards and create a schematic for you and then tell you how to assemble everything. I nor anyone else is likely to get any enjoyment out of doing all that leg work for you.

My suggestion: Research. Draw a schematic. Assemble it. Troubleshoot. Play.

Except I'm NOT asking for someone to explain it to me, READ --THEN--- RESPOND.

I already have my plan posted above, I already explained that I know HOW it works and WHY it works.

I just want a simple "yes" or "no" from someone who has already done this, and if I can use the capacitor already on the board.

did I get it right? if so, cool.
if not, I'll go back to doing my own research like I did in the first place.

I know it will save data and keep the WRAM safe, but will it last as long as a normal cart, or did I screw up the wiring and cause the battery to drain too fast? I can't test that any way besides running the console for hours.

Here's the damned schematic.

Your schematic is fine.

I wouldn't reuse the cap on the board because you still need that cap for the other ROMs on the board.

You forgot a 10k pullup resistor for CS and WE.

is that necessary?
It's the first I've heard of needing another resistor.

This is for the /ce pin on the wram right?
Why does that need a resistor?

My guess is that it helps ensure that the voltage on that signal is well defined even while the Control Deck is powering on or off.

tepples wrote:My guess is that it helps ensure that the voltage on that signal is well defined even while the Control Deck is powering on or off.

Exactly. If you don't pullup these signals to backup power, your data can be corrupted. To be honest, you must build this schematic:

Or use some specific IC, for example BA6162:

And your data will be saved for years. I have Light Crusider cartrige for Megadrive and save files are works after 5 years from last use.

HardWareMan wrote:And your data will be saved for years. I have Light Crusider cartrige for Megadrive and save files are works after 5 years from last use.

While that circuit is probably drastically better than the original circuit most people don't have issues with the original one provided you do put the pull ups/downs on /CE(CE) respectively like you pointed out.

One thing is your circuit doesn't affect the lifetime of save data in regards to years. It protects it when inserting/removing and power on/off the cartridge which is where most problems arise. But the lifetime (years) a that the data will be maintained mostly depends on the static power consumption of whichever SRAM you choose, and the shelf life and quality of the battery.

I've had data maintained with Nintendo's standard battery backing last from when I played as a kid nearly 20 years ago.

infiniteneslives wrote:One thing is your circuit doesn't affect the lifetime of save data in regards to years. It protects it when inserting/removing and power on/off the cartridge which is where most problems arise. But the lifetime (years) a that the data will be maintained mostly depends on the static power consumption of whichever SRAM you choose, and the shelf life and quality of the battery.

Exactly. But we assume that SRAM is a low power one and battery is good one, isn't it?

HardWareMan wrote:Exactly. But we assume that SRAM is a low power one and battery is good one, isn't it?

Assume what you'd like, but there are lots of SRAM's that don't have low static power. There are also lots of dead/cheap batteries in the world. It depends on what you choose...

infiniteneslives wrote:

HardWareMan wrote:Exactly. But we assume that SRAM is a low power one and battery is good one, isn't it?

Assume what you'd like, but there are lots of SRAM's that don't have low static power. There are also lots of dead/cheap batteries in the world. It depends on what you choose...

OK, you win.