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Author Topic: SNES ROM Types  (Read 12545 times)

Divayth_Fyr

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SNES ROM Types
« on: September 26, 2017, 10:35:30 pm »
I know there are a couple of different file types for SNES ROMs.  But I couldn't find any information about what the differences between them are?  When does it actually matter?

KingMike

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Re: SNES ROM Types
« Reply #1 on: September 27, 2017, 01:23:57 am »
Despite different file extensions, usually the only difference in ROMs is if they have a header or not.

Headers are 512 bytes of extra data that might have meant something if you owned the very old copiers they were from. (otherwise it only matters if A header exists, not what that data actually is) But I would imagine that would apply to only a very small amount of people, seeing as how both of the means they usually used to copy ROMs to the device are no longer available on modern PCs (floppy disks and parallel ports).

SNES ROMs can be "interleaved" which means the data has been shuffled around in some way but I've only seen that on a few ROMs out of hundreds/thousands over many years of playing emulators. The majority of ROMs you would find these days have been run through ROM auditing software which usually only catalogs unchanged ROM data.

higan (formerly known as bsnes) has adopted its own format which it will convert standard SNES ROMs into, but that is a different topic in itself.
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Psyklax

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Re: SNES ROM Types
« Reply #2 on: September 27, 2017, 03:15:59 am »
I'm not sure precisely what the OP is referring to, but I can think of three ways SNES ROMs can be differentiated: .smc or .sfc extensions, header or no header, HiROM or LoROM. The first two are not really much different at all, and the last one is only of interest if you're a ROM hacker.

KingMike

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Re: SNES ROM Types
« Reply #3 on: September 27, 2017, 02:05:35 pm »
There's a boatload of dead SNES ROM extensions: .swc, .fig, .058, .078 are just the ones I can remember. Old floppy/parallel copier junk.
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Psyklax

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Re: SNES ROM Types
« Reply #4 on: September 27, 2017, 02:44:20 pm »
There's a boatload of dead SNES ROM extensions: .swc, .fig, .058, .078 are just the ones I can remember. Old floppy/parallel copier junk.

Maybe, but those virtually never turn up. I presume the OP was referring to something else.

Divayth_Fyr

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Re: SNES ROM Types
« Reply #5 on: September 27, 2017, 10:26:43 pm »
OP here.  Sorry for the ambiguity.  Mostly I wanted to know what the major difference between .sfc file and a .smc is.  I'm also wondering if it actually matters for hacking.  Consensus seems to be that the only difference is headers. Still it would be cool if there were format guides to describe what the memory locations mean.  But I'm really just getting started so I guess it doesn't matter right now.  Thanks all.

maseter

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Re: SNES ROM Types
« Reply #6 on: September 29, 2017, 04:54:48 pm »
Byuu (bsnes/higan creator) said over at smw central once:

Quote
The extension is unimportant, the actual format is 100% identical.

.smc stands for Super Magicom, which was one of the earliest SNES copiers. The irony is that 90% of dumps come from SWC DX2s and GDSF7s.

.sfc stands for Super Famicom, which makes a whole heck of a lot more sense.

Unfortunately, the former caught on in the early days because the first dumps were distributed that way through piracy BBSes and such. It continues to exist because the most popular (and lowest quality) SNES organization tool still uses SMC.

I would ask that you guys use SFC, simply run "ren *.smc *.sfc" in your ROM folder, but I can't make people change.

Sorry, no go Byuu, as an emulation purist, i ONLY play sfcs dumped by the Super Magicom! :)
« Last Edit: September 29, 2017, 05:00:48 pm by maseter »