nesdev.org

Ive been casually looking for one of these things for nearly a year now messaging the owner every time one is listed on the Ebay in my country but to no avail

Does anybody know or have an idea numbers wise how rare these things are and if anybody has ever found one outside the Us?

Also, if i become desperate and resort to doing a conversion whats better, Tk or Ts rom? Does the battery from Tkrom work as is? or does it need rewiring? AND for the last of my annoying questions how on earth do you go about fabricating the missing pin?

EDIT: Ok ive managed to track down a few of the full pined mario's so now i just need the 2nd doner for the ram. Do all the nes games that use ram have 8kb ? or do some have higher or lower? And whats a cheap common cart (Euro release) that has has 1-2 8kb ram chips?

Thanks

The first person I asked who had two SMB2s said one of them was full-pinned. But he wanted to sell me three common NES games for $20. I tried haggling it down & he said "forget it."

I gave up looking in my home country and decided to start asking people on Ebay Us and surprised how many i found. There not that rare at all, infact one seller replied telling me a way you can tell if they are full pinned by the label! Im not sure how accurate it is but i will find out soon enough when they arrive in the mail.

Well seeing how many billion people mention it at this rate they'll all be turned into FF3 carts shortly. (which is not completely a bad thing considering how good FF3 is (but the last dungeon is HARD) even if we here don't support people making repros)

Bregalad wrote:Well seeing how many billion people mention it at this rate they'll all be turned into FF3 carts shortly. (which is not completely a bad thing considering how good FF3 is (but the last dungeon is HARD) even if we here don't support people making repros)

Hey Bregalad, i was reading over some previous threads and you seem to be the go-to guy about adding batterys to Tsrom and other non battery carts. Seeing as you posted could i ask you if this is right?

http://nintendoallstars.w.interia.pl/romlab/msram.htm

Thanks

By full-pin, are you talking about the full set of pins on the cartridge connector? I have one of those. Bootgod's site doesn't even have a scan of a US SMB2 cartridge that doesn't have the full pins.

NO this site is NOT right if you do it like they say your chip will be constantly powered by the battery and never by the main supply and this is BAD BAD BAD !!

To have it done right you need 2 diodes, one from the main power supply, and one from the battery, each going in series with a ~1k resistor.

Bregalad wrote:NO this site is NOT right if you do it like they say your chip will be constantly powered by the battery and never by the main supply and this is BAD BAD BAD !!

To have it done right you need 2 diodes, one from the main power supply, and one from the battery, each going in series with a ~1k resistor.

Excuse my ignorance but whats so bad about it running from a battery all the time? Does it just drain faster?

Edit: Never mind. Did some reading. So basically it should be like this


Battery+-----(diode)----------Sram bent/cut power pin---------(diode)------Power pad/trace on board


?

Yeah there is a few things that are bad : When the cart will be plugged in a powered UP NES, the data and adress lines on the SRAM chip will toggle between 0V and 5V levels. Since the VCC pin will have a ~3V voltage, it will be a bad thing. There is usually diodes connected between input pins towards the VCC pin, so this will effectively force the VCC to ~4.3V, and might drop even lower if the chip is active and draws current.
So this circuit sort of RELIES on those internal diodes - but there is no guarantee all SRAM chips have them. In fact it'd be perfectly possible that they aren't present, and that will damage/fry the chip.

Drawing current from the adress/data/control lines instead of VCC is BAD because not only the traces on the circuit are thin and weren't designed to draw any current, but all the current drawn will be drawn trough the CPU that is inside the NES that wasn't deisnged for that and this is BAD.

Another bad thing is that as soon as all your data and adress lines will have 0V level (for example if you write to $6000 that will happen), the chip's voltage will suddently drop to battery's 3V and this is BAD.

So you'd better want a reliable power supply that makes sure the chip is always powered by the 5V power supply and that slowly drops to 3V when the power is off (that's why it's a good idea to add a >1uF capacity in parallel with the VCC pin : it will ensure slow transitions from 5V to 3V and reduce risk to loose saves.

So short answer : if you do it like ROMlab does, SRAM operation will be unstable, read/writes to/from it won't always work, and both the CPU in the NES and the SRAM in your cart might even overheat due to current being drawn in Adress/data/control lines instead of power supply.

Ok, thanks so much for taking the time to write all that up. Had you not, i probably would have gone ahead and used the romlab diagram and ruined my game and nes!

So with the resistors in parallel now it would go


Gnd----Battery------Diode----------Sram-----------Diode------------Main power
..................................|--1k resistor--|--1k resistor--|

(the dots are to keep the resistors in the middle, without them then just go the left)

?

The first resistor comes in series with the diode between the battery + and the RAM VCC (it electrically doesn't matter in which order the diore and the resistor are).
There was a second resistor but to be honnest I really can't remember where it was placed. You should look at a Nintendo circuit to know for sure.
I'm also pretty sure a third resistor is necessary to ground /OE of the SRAM. At least for the MMC1 it was necessary, but maybe the MMC3 has an internal pull-down I'm not sure.

Also be sure to place the diodes with correct polarity (cathode = where the dash it = side of the VRAM VCC).

Allright, thanks for all your help. I will do some comparisons between Tk and Ts rom and then experiment until i get it right.

Ok, i hate to ask another question and drive this thread even FURTHER off topic but i thought its better than cluttering the board with a new one. I dont know how appropriate this question is so if you've got the answer its probably best to send me a pm.

While i wait for my Mario 2's to arrive for ff3 i thought id knock up and play a ff2 to pass the time. I used the ff2 lost translation on a zelda cart and when i boot it up i get the blue screen and a bunch of garbled text scrolls across and then it freezes.

I know the prototype rom would probably work but the translation is terrible. So if anybody knows if theres a good english translation that works on the hardware please let me know.

SnesGuy wrote:I used the ff2 lost translation on a zelda cart and when i boot it up i get the blue screen and a bunch of garbled text scrolls across and then it freezes.

That translation was made before we understood a lot of things about the PPU. I don't recall exactly what's wrong with it, just that it does Bad Things.

The official prototype is probably your best bet, unfortunately. :\

BMF54123 wrote:

SnesGuy wrote:I used the ff2 lost translation on a zelda cart and when i boot it up i get the blue screen and a bunch of garbled text scrolls across and then it freezes.

That translation was made before we understood a lot of things about the PPU. I don't recall exactly what's wrong with it, just that it does Bad Things.

The official prototype is probably your best bet, unfortunately. :\

Damn, thats what i was expecting. Is there a good/accurate 1:1 Nes emulator that will only play what the Nes can so i can test the roms before i burn? Nestopia will run anything no matter how bad it is.