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rocket

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i am thinking this flash ram stick would work for triforce and chihiro also. Those definately store the scores on the ram.
 

Fluffy

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Flash works different from RAM. You need to use a special algorithm to write to it.
 
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Why not make some flash ram dimms for the net dimm. Would keep the data and not need the battery. You get your quick boot time and data retained. Could swap sticks and keep high scores retained.
That's what I proposed two posts before yours. :)
 
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Flash works different from RAM. You need to use a special algorithm to write to it.
Depends. I've substituted RAM with flash before and it worked just fine. I guess it depends of the brand, size, etc.
 

brizzo

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The difficult thing will be that some carts seem to have a Xilinx CPLD or FPGA device on them
Indeed, it took me approx 400 hours to reverse engineer the logic and re-create the security algorithm it implements.
 

Fluffy

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Indeed, it took me approx 400 hours to reverse engineer the logic and re-create the security algorithm it implements.
Does it sit on the bus between ROMs and motherboard, or is it separate? Do you have any notes or pinouts you don't mind to share?

Edit: Ok, I'm caught up on the thread. :) And I had a peek at the mame driver for Naomi and the decryption.

So, do I understand it correctly and the repro PCB would just be a 171-7919A without the protection gubbins? Or is anything of that still used by the game, like some DMA hardware?
Would it be worth integrating the 27c322 with the other ROMs into one linear map, so that there is room for the "leftover" bits?

(Slightly off topic: Is it worth buying a Naomi 2 or Naomi 1?)
 
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brizzo

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Does it sit on the bus between ROMs and motherboard, or is it separate? Do you have any notes or pinouts you don't mind to share?
The FPGA sits across the entire bus, the cartridges function as an extended G1 bus device. Flash and PIC are both controlled through it's logic.

Do you have any notes or pinouts you don't mind to share?

Edit: Ok, I'm caught up on the thread. And I had a peek at the mame driver for Naomi and the decryption.

So, do I understand it correctly and the repro PCB would just be a 171-7919A without the protection gubbins? Or is anything of that still used by the game, like some DMA hardware?
Would it be worth integrating the 27c322 with the other ROMs into one linear map, so that there is room for the "leftover" bits?

(Slightly off topic: Is it worth buying a Naomi 2 or Naomi 1?)
I reverse engineered and have made a reproduction cartridge based on the "M4 cartridge" (Part number 171-8346C). This is backwards compatible with all other cartridge types/games. But given the parts cost it doesn't make economic sense to produce a single game cartridge.

There is additional copy protection on real hardware that is not part of the MAME emulation. The algorithm provided by the PIC is only one piece of the puzzle. Even running decrypted games is not simple and it is not possible to create a flash only pcb without the g1 device logic. It is also not possible to modify the naomi bios either as nobody has been able to solve the checksum algorithm to date.

N1 is more reliable than N2; they are notorious for issues.

Depends. I've substituted RAM with flash before and it worked just fine. I guess it depends of the brand, size, etc.
512mbyte PC-133 SDRAM :)
 

Fluffy

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I don't plan to implement the encryption, it would need to be "net-bootable" versions in the first place.
Is the minimum "flash + G1 device", or is that protocol protected as well before the bios attempts to use it?
 

brizzo

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I don't plan to implement the encryption, it would need to be "net-bootable" versions in the first place.
Is the minimum "flash + G1 device", or is that protocol protected as well before the bios attempts to use it?
I skipped on the encryption as it is not required. The g1bus protocol is not specifically protected, but it uses additional commands that are not documented along with a challenge/response algorithm that authenticates the cart (it's a fun one, starts with a random seed and continues while running)
 

obcd

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Only outrun 2 SP on chihiro uses part of the dimm memory for it's high scores and settings. Most other games use the battery backupped nvram on the base board.
It's basically a type 3 game as the partition used for the high scores doesn't exist on a type I dimm setup. I have no idea for triforce.

As a dimm uses sdram for it's storage, it will use some kind of memory refresh.
It might use auto refresh so that the memory takes care of it's refresh itself.

Dreamcast had some biosses that could load games from a harddrive. Wouldn't it be possible to create such for a naomi or do they differ 2 much?

On chihiro, the differences between it's bios and that of an xbox aren't that big, but that's total different hardware obviously.
 

MetalliC

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The FPGA sits across the entire bus, the cartridges function as an extended G1 bus device.
probably worth to mention - there is 2 kinds of cartridges
- older/simpler type like 171-7919A, with only small PLD device. in this case G1/ATA bus access logic handled by Altera FPGA at main board, and this FPGA provides special rom board bus at CN3 connector.
- newer type, like 171-8346C with FPGA device, which sits directly at G1/ATA bus (CN1 connector) and do everything on it's own.

as far as I know - simpler type at this point is completely black box, nothing known about it's internals, or CN3 bus, etc.
while newer type with on-cart FPGAs was RE'd by brizzo.
 
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Fluffy

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I've got a Derby Owner's Club on the way, which is 171-7919A. It was the cheapest cart I could find, and a game I don't care about in the slightest. :) Even if it is completely broken it should be enough to look at the PCB and the connectors.
I am not sure how much I can get done this side of Brexit, but at least I'll try to have a look at the layout. I try to not buy big things at the moment that will make moving more difficult, so it will be next month when I can look at getting a Naomi and the required wiring.
 

MetalliC

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I've got a Derby Owner's Club on the way, which is 171-7919A
please check if it maybe undumped revision, older DOC versions which uses 171-7919A is not common and I suppose we might miss some of these.
while most common at ebay DOC World Edition uses 171-8132B rom board type.
 

obcd

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Derby Owner's Club is pretty big for the man's cave...
 

Fluffy

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please check if it maybe undumped revision, older DOC versions which uses 171-7919A is not common and I suppose we might miss some of these.while most common at ebay DOC World Edition uses 171-8132B rom board type.
I looked up the board from the dumped ROM list, so until I open it I don't know what'll be in it. If it is anything rare I'm going to get it dumped.

Derby Owner's Club is pretty big for the man's cave...
Well, I couldn't find a Ridge Racer Full Scale.
 
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