Overdumped Roms

[Jeffrey]

This question applies to Sega, but I have to use a recent Nintendo example. I was eager to preview the new (retro) Famicom Mini series for the GBA.

I saw the roms on some site. The first, Super Mario Bros., was 24M. That is pretty big for an 8bit game. Zelda, which should be much larger if not equal to SMB, was only 0.75M. That seems about right for an old 8bit game!

So what is the difference? I have seen this before in MD roms as well. I have also heard the term "overdumped". Can this be fixed? Can the excess be trimmed or is it a design flaw in the program?

Most of the other games on the series vary as well. Donkey Kong was 8M, Pac Man 0.25M, River City Ransom 32M. It is also a sega problem, but the size of Sega roms make it less pronounced. Can anyone explain this to me?

 

[Mask of Destiny]

An overdump simply means you dumped past the end of the cart. Fixing it is as simple as chopping off the extra data.

In your example; however, it's possible that the cartridges are indeed that big (sometimes its cheaper to use bigger chips for availability reasons) and they might just be mostly empty. The smaller ROMs you found may have been trimmed to cut out some of the useless filler.

 

[ExCyber]

AFAIK, overdumped ROMs don't usually have filler for the overdumped portion, because it would actually take extra hardware to confine the ROM to an address space equal to its size (basically you would have to have a decoder/demux with one of its outputs going nowhere).

 

[gameboy900]

Overdumped roms can also be caused by incorrect read sizes. So for example reading 2 bytes for each address instead of just 1. In this case just trimming the end won't help since you would need ever other byte.

 

[Myname]

River City Ransom isn't in the Famicom Mini series though, it's a new version with updated graphics. That still sounds way too big though..

 

[Mask of Destiny]

Originally posted by ExCyber@Mar 8, 2004 @ 12:54 AM

AFAIK, overdumped ROMs don't usually have filler for the overdumped portion, because it would actually take extra hardware to confine the ROM to an address space equal to its size (basically you would have to have a decoder/demux with one of its outputs going nowhere).

The filler comment was in reference to the possibility of them using a larger masked ROM than was needed for cost/availability reasons. An 8MB masked ROM with only 512K of data would be mostly filler.

 

[Jeffrey]

I guess it doesn't matter now! I lost DK and SMB when I had to restore my computer because of a really bad worm!

I can't find them any longer! Damn.

 

[antime]

Fortunately for you, you can just buy them. Aren't you lucky?