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Author Topic: What is a header in a patch?  (Read 4140 times)

failrunner

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What is a header in a patch?
« on: September 14, 2014, 09:33:50 am »
I know what it means if you're talking about a letter or webpage but I have a retron 5 and there is an option called "expect header" and I see people mentioning it all the time here but I don't know what it is and if I sould check the option to expect it or not.

BlackDog61

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Re: What is a header in a patch?
« Reply #1 on: September 14, 2014, 10:12:50 am »
Some old platforms didn't have space reserved in cartridges to give info about a game (name, developer / producer, a small icon...) it is standard nowadays to see this for a game before you launch it, so emulators for old systems have taken a habit of adding the info to the game, even if the real original hardware wouldn't expect that extra data to be there.
There's probably info to be gathered from the documents section on this?

puzzledude

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Re: What is a header in a patch?
« Reply #2 on: September 14, 2014, 12:51:17 pm »
Quote
What is a header in a patch?
Patches have no headers (well actually they do, but this is usually 5 or 6 bytes for IPS and the option "expect header" does not refer to that), but roms do, original roms or modified roms (aka hacks). However, a patch can be done from a headered rom. A patch (usually IPS), is a series of commands what bytes to change and where. Imagine you make an IPS from a headered rom (then obviously all changes are 200 bytes in hex shifted in comparison to the IPS done from a non headered file).


Quote
I know what it means if you're talking about a letter or webpage but I have a retron 5 and there is an option called "expect header" and I see people mentioning it all the time here but I don't know what it is and if I sould check the option to expect it or not.
The file header are 200 bytes in hex (or 512 in dec) at the beginning of the rom file (mostly 00 bytes). It is a copier leftover or pure ballast (basically a leftover while "converting" from a "cart" into the rom file).

Of course you also have the internal header (for instance SNES internal header, where the actual main info of the file is stored, thus making the file header irrelevant).

Most of the emulator ignore the file header but hyper retron might not. The option "expect header", is most likely the file header. And if the hyper retron has this option, then the header issue is solved.

If you have the cart with the headered original rom and an IPS patch which requires such a rom by default (for instance SMW, since all hacks with SMW usually need a headered original rom), then you should have this option checked, and the system will thus support IPS patches, made for headered original roms.

However, on the main site of hyper retron, there is a message that the system doesn't support Ips patching for headered roms.
In that case this is just less important option then, that will simply tell the system to read (display) the info in the header. This option could also be there to allow headered original roms. In this case it is a safety, specially if the original hardware didn't expect those extra bytes to be there.



« Last Edit: September 14, 2014, 12:56:52 pm by puzzledude »