Author Topic: SMS Myth Cart - how to get these ROMs to run?  (Read 9797 times)

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Offline amptor

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SMS Myth Cart - how to get these ROMs to run?
« on: April 11, 2011, 10:09:02 AM »
Hi these ROMs are common.  A couple of examples: Strider and Outrun.  The file sizes are odd in the goodsms set and when I load them onto the cart, they don't load on the sega master system from the menu.  they just stay at the menu and the system freezes.  Reset button doesn't function in this case.

Let me know if there is any way to fix these.  I tried to pad them and that didn't help.

Also Street Fighter 2 is like 800k which is also an odd size but it works fine.  The program gives me an error before it is displayed in the list of games but it still programs and runs fine.

Also are there any updates for this? I only see 3 threads for this device which is somewhat strange imho.

Offline mic_

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Re: SMS Myth Cart - how to get these ROMs to run?
« Reply #1 on: April 11, 2011, 04:21:22 PM »
I haven't tried these specific games, but I could check it out.

I wasn't aware that they had started selling the SMS cart, which is why there haven't been any updates. We (ChillyWilly, Conle and myself) have already created an updated menu which is more or less done, but we haven't released it yet (though the source is available at the google code neo-myth-menu repo.. if you have SDCC installed and feel adventurous). I think ChillyWilly is working on finishing the SD support code, but he might be prioritizing the MD and N64 menus.

Offline Aleomark

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Re: SMS Myth Cart - how to get these ROMs to run?
« Reply #2 on: April 11, 2011, 09:16:24 PM »
I wasn't aware that they had started selling the SMS cart,...

Me neither, also it isn't listed in ic2005

Offline Conle

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Re: SMS Myth Cart - how to get these ROMs to run?
« Reply #3 on: April 11, 2011, 09:43:00 PM »
I tried to pad them and that didn't help.

Did you tried to byte-align it by 512bytes ?

Offline amptor

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Re: SMS Myth Cart - how to get these ROMs to run?
« Reply #4 on: April 12, 2011, 12:14:19 AM »
I haven't tried these specific games, but I could check it out.

I wasn't aware that they had started selling the SMS cart, which is why there haven't been any updates. We (ChillyWilly, Conle and myself) have already created an updated menu which is more or less done, but we haven't released it yet (though the source is available at the google code neo-myth-menu repo.. if you have SDCC installed and feel adventurous). I think ChillyWilly is working on finishing the SD support code, but he might be prioritizing the MD and N64 menus.

Oh so it is getting SD support as I would have expected.  When do you think we might see a new menu out?  Maybe it could use an updated writing software to resolve the issue with odd sized ROMs too.


Did you tried to byte-align it by 512bytes ?

How would I go about doing a byte-align?  What software would you suggest?  I was having a difficult time last night finding a padding software so I just used ucon which isn't exactly my best choice for non-snes/non-md roms.

Offline mic_

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Re: SMS Myth Cart - how to get these ROMs to run?
« Reply #5 on: April 12, 2011, 01:02:39 AM »
Strider seems to have some sort of copier header. You'll also need to fix the checksum if you modify the file.

Here's a tool you can use, which also automatically updates the checksum: http://jiggawatt.org/padsms.zip

The way you'd use it to fix Strider is:  padsms.exe Strider.sms Strider_fixed.sms 512 512
(the first 512 is the new size in kB, and the second 512 is the number of bytes to skip at the beginning of the file)

Offline amptor

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Re: SMS Myth Cart - how to get these ROMs to run?
« Reply #6 on: April 12, 2011, 02:11:45 AM »
Strider seems to have some sort of copier header. You'll also need to fix the checksum if you modify the file.

Here's a tool you can use, which also automatically updates the checksum: http://jiggawatt.org/padsms.zip

The way you'd use it to fix Strider is:  padsms.exe Strider.sms Strider_fixed.sms 512 512
(the first 512 is the new size in kB, and the second 512 is the number of bytes to skip at the beginning of the file)

cool thanks Mic I will try it when I get home.  Interesting that Street Fighter 2 worked with no issue @ 800kb I guess that means it doesn't have a copier header then.  I'll have to try this method on those 2 ROMs I mentioned earlier including Strider.  Hopefully it works.  I'm happy with the homebrew support on this.  Only minor issues possibly due to improperly coded ROMs.  It appears that much of the homebrew support for this console has been for the great emulator called Meka.

Offline ChillyWilly

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Re: SMS Myth Cart - how to get these ROMs to run?
« Reply #7 on: April 12, 2011, 03:26:55 AM »
One issue I've run into with homebrew on the SMS is much of it ignores real hardware constraints. Primarily, they writing the VRAM at full speed all the time. The problem is that you can only write the vram at full speed during the vertical blank. Outside the vertical blank, you can still write the vram, but you have to use a slow loop that allows enough time between writes for the SMS to finish writing the vram (29 T-states). Now that SMS flash carts are appearing, we'll probably see people go back and fix the problems now that they'll be able to test on real hardware.

Offline amptor

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Re: SMS Myth Cart - how to get these ROMs to run?
« Reply #8 on: April 12, 2011, 11:44:39 AM »
Ok guys I'm pleased to say that the tool to fix the checksum and header worked 100% and now every ROM I have tested on it, besides a few homebrew, work fine.  So now I can wrap up this product review testing.

Thanks for all the help and hopefully the product and updates get released soon.  I still need to try out the new SNES menu and see where you guys are at with the N64 but the current one I have for N64 works great.