News: 11 March 2016 - Forum Rules

Author Topic: Do Sega CD titles verify checksums?  (Read 2382 times)

4lorn

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Do Sega CD titles verify checksums?
« on: February 22, 2020, 06:57:36 am »
Hi. Probably a stupid question I'm sure, but I've noticed people took a liking to my Genesis Flink hack that removed the buildup walking speed, and some mentioned it would be nice to have a hack that did the same for the CD version.

So I went and did that this morning for US/EU and *.img/*.bin+cue variants, and it runs fine on emulators (tested with gensKMod_073 and Fusion 3.64), but I'm wondering if this would work on emulators that do not auto-fix the checksum and by association, on real hardware.

So as per the thread title, do they?

Tony H

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Re: Do Sega CD titles verify checksums?
« Reply #1 on: February 22, 2020, 10:18:15 pm »
I'm not 100% sure, but I don't think they do a checksum check on Sega CD games.  Someone please correct me on this if I'm wrong.

I've done a lot of iso hacks on Sega CD games, and have never had an issue.  I often use Gens for SCD, and I know that it doesn't automatically correct checksums for Genesis games (I'll get the red screen when there is a bad checksum). 
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goldenband

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Re: Do Sega CD titles verify checksums?
« Reply #2 on: February 22, 2020, 11:35:47 pm »
I can't imagine how a checksum on a full CD could possibly be practical in that era, since on a 1X speed drive it'd require the equivalent of the playing time of a CD, no?

Maybe something that checked the core game files only -- i.e. omitting audio sectors, maybe FMV too -- but even that could take a while, depending on the size of the game executable.

4lorn

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Re: Do Sega CD titles verify checksums?
« Reply #3 on: February 23, 2020, 05:07:44 am »
Ok, thanks :) Like I said, it was a stupid question but it was the first time I ventured into SCD hacking and noticed (in Flink's case, at least) that there actually wasn't any checksum value at all, at least when compared to the Genesis version.

Thanks once again :thumbsup: