Question About Neo Geo Mvs Emulation

[DijiTao]

I got to thinking about those big Neo Geo carts again and it occurred to me that since they're read only, why again do we need to pull the entire thing into ram? Is the speed of the rom on a Neo Geo cartridge really that much faster then a high speed SD card? If the games rom is stored un-compressed on the SD card can't the emulator just read it from their just like how an actual Neo Geo reads it from the cartridge?

 

[Minkoff]

That was actually bugging me too.
Because even though SD cards have a limited amount of write cycles, it looks like they can be read without dying.

 

[junker]

YES!
how come no one brought this up before?
running uncompressed games on the SD still beat the iso+mp3 option in size, not to mention a lot more games playable.

 

[craigix]

Yes they really were that much faster.

 

[Squidge]

Reading an SD card - under a meg/second. Reading an MVS cart - several hundred megabytes/second. Hmmm

 

[lucoxade]

I wonder if its too late for GPH to swap the SD slot for battery backed up SODIMMS ?

**kidding!**

 

[reallynotnick]

Reading an SD card - under a meg/second. Reading an MVS cart - several hundred megabytes/second. Hmmm

​

Well mine is supposedly 8.2mb/second.

The real question though is HOW fast does it really NEED to be? It's never going to use all of that bandwith for one level right? It's just a guess, well it seems to be time to be buying those 120x cards

 

[stinch]

It's not just the bandwidth that will be important but the latency as well. When you have a system with very little ram that has fast carts connected directly to the hardware the carts could well be used frequently. Reading data direct from the cart would free up some of the limited ram for other uses.

 

[Prothall]

Reallynotnick: I think - and you can check on this - they like to put SD Card speed in M<em>bits</em>, not M<em>bytes</em>. Makes a world of difference.

 

[whiskthecat]

Reallynotnick: I think - and you can check on this - they like to put SD Card speed in M<em>bits</em>, not M<em>bytes</em>. Makes a world of difference.

​

Man I hate when they put things in bits. It really grinds my gears. :lol:
The only reason they do it is to confuse people and try to make them think they are getting more of something when they really aren't.

 

[Prothall]

Eh, I think there was some point in history where it was the more common measurement, as you can't really substitute another unit for it. Naturally, you're absolutely right about its use these days.

 

[icurafu]

yeah, they use bits in datatransfer because the data is sent alongside error checking bits/partity bits.

If it is storage, it is always bytes.

 

[DijiTao]

The card I'm going to get has a 22.5MB/sec read (http://www.newegg.com/Product/Product.asp?Item=N82E16820211313). Since It's listed as MB and not Mb that *should* mean MegaBytes not Megabits. Now factoring a 33% marketing bs factor that's still 15MB/sec. At that speed all of Garou could be read in less than 6 seconds which seems pretty speedy to me. I however understand how latency could still be an issue, but this is when I come back to the fact that an XBOX with it's 64MBs of RAM and using the hard drive for swap is perfectly capable of running Garou. Is the latency on the fairly unimpressive XBOX hard disk any better then a quality SD card? The topic of using the SD card as swap has come up before but everyone has said that isn't feasible because of the slow write speeds, and the fact that it would wear out the card with all of it's writes, but thinking it through now, why would you have to write to the card at all? So shouldn't you be able to just keep the most frequently accessed parts of the ROM in RAM, and just read the rest off the SD card?

 

[Cahaz]

with a method or another, it doesn't mather. I just hope we'll be able to play every MVS games we want...

Do this, online matchs support , a chatbox, DOSbox and some pc conversions and i'm in heaven.

 

[DijiTao]

Another Interesting way of looking at it is the breakdown of the individual roms (sizes in bytes):

[z80]
253-m1.bin 262,144

[text]
253-sma.bin 262,144

[Graphics]
253-c1.bin 8,388,608
253-c2.bin 8,388,608
253-c3.bin 8,388,608
253-c4.bin 8,388,608
253-c5.bin 8,388,608
253-c6.bin 8,388,608
253-c7.bin 8,388,608
253-c8.bin 8,388,608

[Program]
253-ep1.p1 2,097,152
253-ep2.p2 2,097,152
253-ep3.p3 2,097,152
253-ep4.p4 2,097,152

[Samples]
253-v1.bin 4,194,304
253-v2.bin 4,194,304
253-v3.bin 4,194,304
253-v4.bin 4,194,304

Now is it possible that some of these would be more tolerant to running with more latency and less bandwidth?

 

[whiskthecat]

with a method or another, it doesn't mather. I just hope we'll be able to play every MVS games we want...

Do this, online matchs support , a chatbox, DOSbox and some pc conversions and i'm in heaven.

​

Same here Cahaz.............Same here.

 

[icurafu]

From what I understood, most of the later neogeo games only loaded from the cart between levels, because devs wanted the game to run on both CDs and cartreges. And because the CDrom was only ever 1x, it could only be done between levels, or else the game would onyl be available for the cartrege.

So, even if the game is too big for the 64meg of ram, then it must have been released after the NeoGeo CD, and thus would be designed to load like a CD. Thus it needs to fit on the 7MB of ram on the NeoGeos.

 

[Seibei Iguchi]

because devs wanted the game to run on both CDs and cartreges.  And because the CDrom was only ever 1x, it could only be done between levels, or else the game would onyl be available for the cartrege.

SNK actually released a new neogeo cd model with a tad bit faster cd drive reading and more internal ram it was called Neogeo Cd Z

 

[TheTurnipKing]

I'd guess it still had to support the slower version of the unit for backwards compatability: The faster drive would probably just enable shorter delays as the data is shuttled into the system quicker.

Unless there were "Neogeo Cd Z" specific titles. But by the sounds of it, it was just a Megadrive 2 "recase the system, and try and find ways to cut the cost" job.

 

[sonofx51]

the CDZ has a 1x drive as well, it has more cache so the games load a bit faster.