How does a game cartridge store information?

[BoringSupreez]

I've seen pictures of the inside of a game cart, and I don't see how they would store any of the information for the program. It just looks like a big chip. Doesn't there have to be some sort of place were something is written, like a piece of film, or a disc? How can the data be stored on a green board?

[Opa Opa]

Magic.

[jeffro11]

Is this a serious question?

[MrPopo]

It's hard to describe without getting too technical, but put simply when you apply a voltage to a certain combination of pins the chip will spit out a series of binary which composes the program. Different combinations of pins will call up different sections of the program. Inside the chip is a very complicated series of switches that are hard coded into a configuration that generates the program when you provide the necessary inputs.

[Ziggy]

Yeah, it is kinda hard to explain from scratch, especially if you don't have any prior knowledge to this kind of thing. Game data, in cartridges, is stored on mask ROM(s). See here:

http://en.wikipedia.org/wiki/Mask_rom

But you'll get more info out of the EPROM Wiki page:

http://en.wikipedia.org/wiki/EPROM

You can pretty much think of them as the same thing. A mask ROM is like a hard pressed DVD you'd buy retail, and an E(E)PROM is like a DVD-R that you would buy blank and burn an image on to. Obviously, when you buy a video game cart, it has a mask ROM on it (save for prototypes and whatnot).

Take a look at this SNES PCB for an example...

http://www.snescentral.com/pcbboards.ph ... VC-1J3M-20

That black chip in the lower right hand is the mask ROM, this particular game only has one (it contains ALL game data). Some carts can have 2 mask ROMs. Arcade boards will have many EPROMs. Depends on the size of the game and whatnot. I've never seen the insides of a NeoGeo cart, but I suspect them to have multiple mask ROMs (due to the size of the games).

The big black chip directly above the mask ROM is the SRAM (http://en.wikipedia.org/wiki/Static_ran ... ess_memory). The SRAM is what holds the game save data. If you read the Wiki page, you'll know that it's volatile memory, which is why it needs a battery. If you look at the pic of the PCB, the battery is in the upper left hand corner (coin size).

In between the the battery and SRAM is Nintendo's MAD-1 decoder. For a simple explanation, the MAD-1 allows the SNES to read from the mask ROM or SRAM when it needs to, and write to the SRAM when it needs to. This particular decoder will also allow for a second mask ROM if needed. The MAD-1 is proprietary, only used in SNES carts. Other game carts that have more than one mask ROM (whether it be multiple mask ROMs or an SRAM chip) will need some sort of logic chip.

Below the battery, the last black chip, is Nintendo's lock out chip for the SNES. This is self explanatory. Every thing else is resistors (one for each chip, I believe) and a capacitor. The PCB (green board) itself is what connects all these parts together, which communicate how MrPopo explained.

[Breetai]

10011011

[Ziggy]

[YoshiEgg25]

10011011

9B

[Opa Opa]

10011011

9B

lol.

Is that what it comes out to? I don't remember how to convert those.

[YoshiEgg25]

10011011

9B

lol.

Is that what it comes out to? I don't remember how to convert those.

I converted it to decimal first.