MultiGame Cartridge Project

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

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FARID
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Post by FARID » Fri Jul 01, 2011 9:10 pm

This is really great! That site has a lot of good information. Thanks.

Since I am using Famicom, It seems that I can't use this method :
But why was this reset-button method rarely (if ever) used in production NES or Famicom multicarts? The easiest explanation is that the reset signal we're using from the CIC just isn't present on Famicom cartridges, since they didn't incorporate a security chip on the Famicom.


But trying it, doesn't hurt.

SkinnyV
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Post by SkinnyV » Fri Jul 01, 2011 9:39 pm

Oh sorry I forgot you were using a famicom, that's too bad! Don't waste your time trying it then. Unless we can just simulate that reset signal on the chip using a button installed on the cart... This could maybe be possible.

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FARID
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Post by FARID » Fri Jul 01, 2011 10:05 pm

I can remember once I had a cartridge which worked like this, games changed with pushing reset button!

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Memblers
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Post by Memblers » Fri Jul 01, 2011 11:49 pm

You can make a reset signal by using M2 (phi2) to charge a capacitor. Then discharge the capacitor through a resistor. I don't know what values to select for the parts, or if there's more to it, I haven't thought it through completely. You'd want it to charge and discharge fairly fast, but not so fast that it'll happen during M2's normal operation (where it's toggling with a 50% duty cycle at 1.789mhz).

Wasn't that also the amusing trick that another multicart used by hooking that reset signal up to the clock input on something like the '161? That way resetting it would clock the counter, which results in selecting a game without using a menu.

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tokumaru
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Post by tokumaru » Sat Jul 02, 2011 1:20 am

Memblers wrote:Wasn't that also the amusing trick that another multicart used by hooking that reset signal up to the clock input on something like the '161? That way resetting it would clock the counter, which results in selecting a game without using a menu.
That's exactly what the guy in the link posted by SkinnyV in the previous page did.

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Post by infiniteneslives » Sat Jul 02, 2011 2:42 pm

I haven't looked into exactly how it works yet but this may be of help:

http://nintendoallstars.w.interia.pl/romlab/74ls74.png

Looks to be along the same lines with the cap charging up at first glance.

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FARID
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Post by FARID » Mon Jul 04, 2011 5:34 am

I still have another so called crap! But maybe this is my ace card!! :D
When I found this cartridge I was just looking for its AX5202P and I was so much hasty that I screwed up the board a little when I was desoldering the AX5202P from the board!

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But there is a problem. This multigame cartridge is included so many NROM games! CHR-ROM is also damaged which I couldn't dump it so I don't know how many MMC3 games are inside it. Hopefully PRG and 27C256 are OK. The code for selection screen is inside 27C256. I don't know the function of other extra TTL chips. I have to omit them one by one to find out which one is not necessary!

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kevtris
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Post by kevtris » Tue Jul 05, 2011 9:09 am

FARID wrote:I still have another so called crap! But maybe this is my ace card!! :D
When I found this cartridge I was just looking for its AX5202P and I was so much hasty that I screwed up the board a little when I was desoldering the AX5202P from the board!

I *highly* suggest you invest in a multimeter, instead. This will make it easier to trace the PCB without destroying it in the process. You don't even have to unsolder any chips. Just put a meter in continuity mode with the beeper, and poke around finding how the chips are connected. This is how I used to do it. It was faster than trying to do it visually. And it doesn't trash the cartridge, which still works after the operation.
/* this is a comment */

SkinnyV
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Post by SkinnyV » Tue Jul 05, 2011 9:33 am

A good multimeter is a good investment! I used a crappy one for a while but it's now so much easier with the decent one I bought recently. Like Kevin said, it beat the hell out of desoldering everything. Also, i'm usually able to desolder chip from famicom board with a heat gun pretty fast and resolder them afterward with no damage. It's a bit ghetto but work very fast! Be careful not to do that without good ventilation as breathing the fume could be dangerous though...
Last edited by SkinnyV on Tue Jul 05, 2011 9:46 am, edited 1 time in total.

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FARID
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Post by FARID » Tue Jul 05, 2011 9:36 am

Wow, Kevtris is here! :shock:

I am not so much smart to dump this cartridge without desoldering the chips, on the other hand it is no use of schematic without owning the code for selection screen which is inside 27C256. Anyway thanks for your advice man! :)

By the way this cartridge is not my ace card! It really sucks! It does not even support 1MB for PRG and CHR so I can't use its schematic to build my dream 8 in 1 Kunio Nekketsu series translated to Farsi multigame cartridge. I have to find another crap like the one which Kevtris have or get him find his cartridge and give me a shot from its both sides! :roll:

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Post by SkinnyV » Tue Jul 05, 2011 10:01 am

Hehe that's also my only way to dump cart lol. I managed to dump part of my Bio Miracle bokutte upa cart before learning Kevin already dumped a long time ago:) It's only giving me issue when pirate cart are using 2 ic for CHR and did not figure out yet how to rearrange and shift the data for those special case...

By the way Farid, do you use a genuine Famicom or a Famiclone? I have recently acquired a pirate multicart with alot of MMC3 game on it but it is not compatible with genuine Nintendo or Famicom console apparently and was developed with clone system in mind. It's actually the best multicart I have ever seen and come with very good game on it, a shame I can't enjoy it on my Nes! The cart is using Flash memory, Chinese pirate have apparently switched to flash as this is the 3rd time I see flash chip in pirate cart.

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FARID
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Post by FARID » Tue Jul 05, 2011 11:27 pm

Memblers wrote:You can make a reset signal by using M2 (phi2) to charge a capacitor. Then discharge the capacitor through a resistor. I don't know what values to select for the parts, or if there's more to it, I haven't thought it through completely. You'd want it to charge and discharge fairly fast, but not so fast that it'll happen during M2's normal operation (where it's toggling with a 50% duty cycle at 1.789mhz).

Wasn't that also the amusing trick that another multicart used by hooking that reset signal up to the clock input on something like the '161? That way resetting it would clock the counter, which results in selecting a game without using a menu.
Can you suggest me some values for those Capacitor and Resistor? I can test some combinations of them. Please give me a diagram too. Thanks

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infiniteneslives
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Post by infiniteneslives » Wed Jul 06, 2011 12:01 am

If you use the circuit I provided the link to eariler the diagram uses a 102 capacitor which is a 1000pF (1nF) cap a diode and 74LS74 chip.

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FARID
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Post by FARID » Wed Jul 06, 2011 5:32 am

I *highly* suggest you invest in a multimeter, instead
I want to listen your advice. :) Do you think this multimeter can meet my needs :

MULTIMETER (PDIP ATMega8 version)

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If you know any better one, please let me know.

infiniteneslives wrote:If you use the circuit I provided the link to eariler the diagram uses a 102 capacitor which is a 1000pF (1nF) cap a diode and 74LS74 chip.
This is great, Thanks! :D

Do you think this can work :

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How does it work : By hijacking A19, A18, A17 the AT27C080 function as eight AT27C010 because Signals of A19, A18, A17 can produce 8 different combinations (000, 001, 010, 011, 100, 101, 110, 111) which at a time just one of them can be activated by pushing reset button so it is possible to use eight 256 KB (128PRG+128CHR) games by using this method.

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I have not test it yet. I just conclude the idea by combining these two information :

NES Custom Multicart - Super Mario All-Stars

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If you've read my other tutorials, you might recall my mention of a chip called a 74xx161 (xx being LS or HC, doesn't matter in this case), which was used as a basic mapper in early NES games. The 74xx161 is a 4-bit synchronous binary counter. Basically, upon each strobe of the clock pin, the binary value of the 4 output pins increases by 1. While the output counts up from 0 to 15, then starts over, if you just consider the lowest two pins, you might be able to picture how it can rotate between 4 different digital addresses.
The largest 8-bit EPROMs are 27C080 or 27C8001 EPROMs, which are 8 Mbit in size. which is equal to 1 MByte. Which means each "bank" of ROM space must be 1/4 of this, which is 256KB. 4 banks, 4 combinations of signals (00, 01, 10, 11) coming off the two pins from the binary counter, get it?
In essence, what we're doing is hijacking the two highest address pins of the EPROMs, and letting the NES only choose the lower address pins (A0-A17), so it only sees a 2Mbit ROM space at any one time.
Could you go for 8 banks by using three bits from the 4-bit counter, or 16 games using all four bits? You bet, but then you need your ROMs to be 128KB each for 8 games or 64KB or less for 16 games. The largest ROM included on this multicart will be the 256KB Super Mario Bros. 3 PRG ROM, and to keep the logic simple, this will be the size of each ROM bank.
Is this sort of mod possible for other cartridge-based systems? Probably. This project takes advantage of the fact that +5V is supplied to the cartridge at all times, even when in reset mode, and it also provides a direct link to the reset signal. I'm not sure this applies to all systems. Other systems might cut power to the cartridge, or might simply not provide any means of detecting a reset.
And :

74LS74 used in many 2in1 Reset based carts

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I want to know what is the difference between 74xx161 and 74xx74? Which one is better for my purpose? Even if there is a better choose other than these two, specially something smaller, please let me know.

What is the full part number of D(148)?
Last edited by FARID on Wed Jul 06, 2011 8:14 am, edited 3 times in total.

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kyuusaku
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Post by kyuusaku » Wed Jul 06, 2011 6:55 am

http://www.dealextreme.com/p/dt-830b-ha ... 6f22-53130
I want to know what is the difference between 74xx161 and 74xx74? Which one is better for my purpose? Even if there is a better choose other than these two, specially something smaller, please let me know.
'161 - 1x 4-bit counter
'74 - 2x 1-bit flip-flops

If you only need 2/4 states (games) use the '74, you can turn it into a 2-bit ripple counter. If you need 5-16 states use a '161.

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