hey, i just want to ask some thing.
Im planning on making a megaman hack and as some of you know megaman is a 128k on a mapper 2 board.
What i want to know is how to mod a mapper 2 for an 27c010 eprom.
There is only PRG files on a mapper 2 board and there on an 28 pin mask rom.
An 27c010 eprom is 128k but it is 32pins how can i put that an the board?
You'll find the instructions here:
http://nesdev.com/NES%20EPROM%20Conversions.txt
excerpt:
UNROM (mapper 2):
Bend up pins 1, 2, 24 and 31
Solder pin 2 to hole 22 (A16)
Solder pin 24 to GND (OE)
It'll just have to hang past the through-holes for the ROM (up where pin 1,2,31,32 are). There may be an axial-lead capacitor there, but you could remove it (would be a good idea to try to keep it there, or at least connected as close as possible to the original spot).
Yeah i seen that.
but will that work with a 32 pin eprom?
Sure it will. That's what the prescribed method is for, it just omits the fact that there are more pins. The rest of the pins are fine. Other people have done it before, only problem I can forsee is if the PCB you're using happens to have the EPROM shoved right up against the side of the case (no extra room). I don't know if there are any boards like that.
pivotman wrote:
but will that work with a 32 pin eprom?
Be honest: You didn't pay attention to what Memblers wrote, did you?
He just said that pins 1,2,31 and 32 will be hanging, because there are only 28 holes, but it will work as long as those pins are bent up and connected to the correct spots with wires.
Most
Nintendo UNROM boards I've seen have that capacitor that gets in the way. So when making my UOROM devcart I used a
Konami UNROM board, which places the PRG-ROM vertically. I don't know if the Konami boards are easy to find, or if they are all like that, but I was lucky to have one.
can't you just solder the capacitor on the "non-component" side of the board?
hyarion wrote:
can't you just solder the capacitor on the "non-component" side of the board?
Yeah, most likely. Depending on the board, it would possibly short out to a ROM pin though from underneath the chip (hidden!), so that would have be considered and prevented. Install the cap before the ROM.
Yeah i do get what he said be im still a little unsure of what im ment to do.
Let me say what i think im ment to do and then you can tell me if in right or wrong.
Bend up pins 32, 31, 1, 2, so that the eprom will fit in the 28 pin socket
also bend up 24
Solder pin 2 to hole 22
Solder pin 24 to GND
is this right?
also what im i ment to do with the pins that are not connected to any thing, do i just leave them alone?
pivotman wrote:
Yeah i do get what he said be im still a little unsure of what im ment to do.
also what im i ment to do with the pins that are not connected to any thing, do i just leave them alone?
Pins 1, 31 and 32 need to be connected to +5V. Pin 30 is +5V so I would just connect them there.
Mitch
OK Thanks.
some i need to bend up pins 32, 31, 1, 2, and 24
Solder pin 2 to hole 22
Solder pin 24 to GND
Solder pins 1, 31, 32 to pin/hole 30
ohh one other thing you know that way it says to solder pin 2 to hole 22 as pin 22 is not bent up can you solder to pin instead of the hole?
Sorry for asking some many questions i just want to make sure i know what im doing before i start!
pivotman wrote:
OK Thanks.
some i need to bend up pins 32, 31, 1, 2, and 24
Solder pin 2 to hole 22
Solder pin 24 to GND
Solder pins 1, 31, 32 to pin/hole 30
ohh one other thing you know that way it says to solder pin 2 to hole 22 as pin 22 is not bent up can you solder to pin instead of the hole?
Sorry for asking some many questions i just want to make sure i know what im doing before i start!
Remember that you have a 32 pin chip and a 28 pin place to install it. The pin numbers do not line up with the hole numbers. Since pin 3 is going in hole 1 it makes all of the numbers off by two. So pin 24 would be going into hole 22, if you weren't bending it up. Make sense now?
Mitch
ohh right i get it now, Thanks for explaining that to me!
Ok i built my cart and i have yet another problem!!
It works but it's really glitchy! to the point the you can't play.
I think it may be the rom, does any one have a good copy of mega man in the mushroom kingdom that works on hardware?
Thanks.
Have you tried to change the mirroring of the chram ?
I just tried that and it works great!
In the rom info it said that mirroring was vertical and when it was in vertical it didn't work.... why would the info be wrong?
Ohh and thanks for your help RGB
Vertical arrangement is horizontal mirroring, and horizontal arrangement is vertical mirroring. The solder pads on Nintendo PCBs reflect arrangement, not mirroring.
I find this thread confusing.
the issue of the capacitor getting in the way somehow led me to believe that the hanging pins were to go toward the center of the cart, where the capacitor lies, according to all images i recall seeing on bootgod's site, and where it is on my Wall Street Kid cart, leading me to resolder and reposition it to sit along the edge of the ram chip.
now rechecking the site I realize that pin 1 is the one closest to the top edge of the cart, where there is a resistor, and therefore the hang-over is on the outer side of the socket, and not the inner side where the capacitor is.
I'm still not entirely sure about this.
That part that looks like a resistor is actually a capacitor.
thank you Memblers. on further inspection, the printed capacitor symbol is neatly hidden in the shadow of what looks exactly like a ⅛ watt resistor. somehow the "C2" and "C3" didn't register in my mind when I examined the board at first glance. I gotta read PCBs for basic information more often.
