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What check sum program used during NES era? I am curious if anyone knows.

Apr 14, 2014 at 10:18:24 AM
Xerxes (20)
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(Xerxes Dole) < El Ripper >
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I am curious if anyone knows what check sum algorithm was used during the NES era. I have noticed that some NES protos have check sums right on the EPROM. Check out the link below if you are curious what I am talking about. I know that these check sums were not created with md5 which is the one that I use. Does anyone know which one was used? It would have been nice if more developers would have done this as would tell us if we have a good dump with no degradation. 

 

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Apr 14, 2014 at 10:57:29 AM
bunnyboy (81)
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(Funktastic B) < Master Higgins >
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They are just a plain sum of all the bytes, no crazy math. Many hex editors and chip programmers will show it to you when you load the file.

Apr 14, 2014 at 5:11:09 PM
Xerxes (20)
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(Xerxes Dole) < El Ripper >
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Thanks bunnyboy. Bit rot only goes one direction right? Which way would it go? 1 -> 0 or 0 -> 1? Would we expect a check sum generated that way to increase or decrease with bit rot?

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Apr 14, 2014 at 5:24:03 PM
bunnyboy (81)
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(Funktastic B) < Master Higgins >
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0->1, but because the sum is more digits than the checksum it could go either way.

May 5, 2014 at 6:14:43 AM
benroveno (0)

(Ben Roveno) < Little Mac >
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Is HEX editor for the color index? Like dfdfdf or FFF (white). Just saying.

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My precious SNES is now stored in my warehouse. Meanwhile, my first-gen Xbox is about to accompany my SNES.
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May 28, 2014 at 1:51:26 AM
GameMachineJames (0)
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My EPROM Programmer is one of those older models. It has a Hex Keypad on it and displays the checksum everytime you program a chip. Soemtimes it asks for you to type in the checksum ahead of time.

Throughout the 200-page manual, it refers to it as "sumcheck" for some bizarro reason. I get a laugh every time.

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I just don't know what went wrong!

I don't even own Super Mario Bros./Duck Hunt yet!

Please help me begin my NES collection! I've already a Caltron 6 in 1, Cheetahmen II, and a handful of commons! I want to start with the rarest games! Bring me your Little Samsons, your Action 52s, your Panesians and your NWC's!


Edited: 05/28/2014 at 01:52 AM by GameMachineJames