So, I guess I only need the ELF files to boot them and they won't show up as corrupt on the Browser? They're not game saves but they show up on their section.
I don't know what you're doing, but if you create a directory without icons - it'll appear as "corrupt data". Each directory on the memory card is considered a save.
Note that it is possible to put as many ELFs as you want in a directory - which is why FMCB has this "APPS" directory. So you, the user, can put your ELFs there without needing to find your own icon.
That's confusing. I don't know which stages are more advanced and some apps have more than one abbreviation.
The answer to your question is that these are still consider works in progress. If there's a version number or release date, then you can tell which are newer.
So, there are ELF, KELF, XLF and XIN PS2 extensions and maybe more and it's because we can usually use the extensions we want it won't screw the files? Why do they even have extensions, then? So, the PS2 community agreed on using some of the previously mentioned extensions (and maybe more), like XLF and XIN?
Again, you can name them as you wish. It's the same on any device - even Windows. Sure, Windows associates programs with file types, using their extensions. But it doesn't change the meaning of each file; you are still able to open files of any extension with the right software.
Like I wrote, extensions are just to hint to the user (and perhaps the OS) what the file contains. Without needing to actually open the file or to already open the program meant to load the file.
So, they didn't have the mentioned extensions (maybe except ELF and KELF) and they were created by random users? Ok, but why call use the "XLF" and "XIN" extensions and not the already existing (if I understood it correctly) "ELF" and "KELF" extensions?
Question: which came first?

Who decides on the extensions anyway. Is there a governing body for this? There isn't really such a thing, so I would say that the software developer (Sony) would have decided on their naming conventions - but those of us outside would not have that information.
The HDD Utility Disc came around 2001, so technically "XLF" would have come first. It's not possible to use a 4-letter extension on an official CD-ROM/DVD, for the PS2.
As for ELF - I don't know for sure whether it's a "standard" extension, as executables on *nix have no extensions. But certainly, as you take a glance at the filename of such a file, you can tell it is an ELF.
I don't understand how can the extensions not usually matter.
1. Create a text file on your desktop.
2. Open it and type something inside.
3. Save the file.
4. Rename its extension to "xyz".
5. Start Notepad again.
6. File -> Open -> Browse to the desktop. Choose to show All Files.
8. Open the file you created earlier.
9. Notice how your work can still be opened, despite you changing the extension.
What's HDD Utility Disc and does it show different extensions than the PS2 when its files are seen (like on the PC)?
In summary, it's a non-game disc which provides a utility for maintaining the content of the HDD unit and to install the HDD Browser.
I got the idea for naming the KELF with the "XLF" extension, because of this disc.
I thought the XLF (and XIN) extension was created by users unlike the ELF and KELF ones but it actually shows up on that HDD Utility Disc?
Yes, so.... XLF is as "official" as it gets.
But as a matter of fact, the "XLF" doesn't appear directly on the utility disc. It's stored within those PAK files, from what I do remember.
Will it overwrite the current FMCB files and/or mess up OSDSYS' entries? May I have problems?
Yes, it will overwrite FMCB. You can choose to keep your FREEMCB.CNF file.
Rightfully, there will be no problems as it's a 1:1 replacement. Particularly if you use genuine memory card and your PS2 has no modchip installed.
What improvements may new FMCB versions have?
You need to refer to the changelog. What you might get, depends on the version of FMCB you are currently using.
The goal of FMCB 1.9x was to support PS2s which the previous versions of FMCB did not - like the PSX (the Japanese DVR unit), the DEX, the SCPH-10000 & SCPH-15000 and the Chinese PS2 (SCPH-50009).
A variation of FMCB, FHDB, adds support for the HDD unit.
The steps for initialization was also improved, resulting in faster bootup. Well, optimizing and writing more technically correct code, were some of my personal goals.
Now what's bad, is that I didn't bother (much) about trying to figure out what causes some problems with certain modchips. Which is why the cleanest experience, can only come from using a clean, unmodded console.
It's partially because my own PS2s have no modchip, except for one. And that one gives no problems with FMCB...
I read
this article and I'm talking about the second paragraph. It the resolution is 480p and not 576p (wasn't it supposed to be 576i, by the way?) I assumed it would look worse.
Resolution refers to the size of the display, in pixels.
The point behind this line, is to tell the reader that "progressive" mode refers to 480P and not 576P - since the latter could be expected in PAL territories.
When progressive mode is enabled on PAL (576i) games, the resolution is 480p, not 576p. Note that not all games from PAL territories support progressive scan mode 480p even if their NTSC U/C counterparts do.
The official SDK only offered 480P (as in, 720x480) as the only progressive-scan video mode.
What do you mean by if the game was already made for it? If the game already had a built-in progressive scan mode, so we don't have to force it via GSM?
Yes. The result would be better than using GSM because we don't have to add additional things behind the game, the game
may be already made to use its resolution and its characteristics.
I was talking about that built-in setting, not GSM, but even so I thought it would look worse when choosing this setting on PAL games.
It boils down to whether the game was made to use the said video mode properly. Whereby it isn't one of those cases where they just made the video simply "fit", by doing things like cutting the screen, not bothering to adapt to the different frame rate and so on.
Than I hope it doesn't mess up my MC since I used the multi-install feature. Is it possible it could screw it beyond repair, like not being able to load my game saves or even using the MC?
I don't think it will physically damage the memory card, but I don't see it as a professional thing to do. On filesystems without support for filesystem-based links, linking multiple directory entries to the same file isn't considered a normal thing.
On Windows, chkdsk would split the conjoined files into 2 duplicates. I'm sure the same will be done for Linux and its filesystems, if fsck encounters something like that.
In the user's perspective, they will appear as multiple files, with the same content. So what happens if the user decides to delete one of them?

The actual file could go missing, and then you will have files with no content.
How would one compute the amount of space consumed, when the directory structure doesn't make sense in the first place (what should the existence of a crosslinked file mean)?
It still doesn't tell me what was done to it. But since you got it from that certain website, I guess it was doctorxyz's recompiled version.
Unless he made some fix or added some new feature, I would say that it's just an unofficial version of the version released by EEUG about 15 years ago.
I don't know because for years I've read people saying to always use the lowest available write speed. What if I don't use IMGBURN or they got the known burning profiles wrong? What if I have an old writer? What do you mean by "old" in this case? I guess the chosen speed has to do with the writer and the used media.
You may need to Google for more accurate answers.
From what I do know, the profiles are in the writer's firmware. When there is no match, AWS will select the lowest speed.
"Old" would mean a writer that was made before your recordable discs were made. It would not be aware of the burning profile for the disc you want to use.
Could you answer the following questions?
No, sorry. Writing such long replies have been taking a lot of my time. I don't even use any of these software you mention.
You could get some answers by Googling. Some of them aren't even about the PS2 and we're in a thread about the PS2. We've long gone off topic too.
4) Is it possible to improve the resolution on PS one Classics/PS1 ISOs on the PS3 and do OPL and other PS2 homebrew tools (maybe OPL and POPStarter?) run on the PS3?
For PS3-related question, you should ask in a new thread, under the subforum for the PS3.
You keep wanting to have better resolution, but how do you suppose the number of pixels should increase? How do you actually enhance the quality of something that was originally poor?
The easy way out, is to just magnify the video for a higher resolution, which might not be what you want as this doesn't improve its quality. There's no "enhance" video feature in this world, which is why that CSI image-enhancing meme exists. It's why "remasters" of games exist, for newer platforms.
There's a PS2 emulator on the PS3. POPS also exists on the PS3 and I'm sure there are ways to play PS games there, so you would not need POPStarter.
10) Could you answer my reply
here?
No. From the PS3 onwards, I only played the games I bought. Since I started playing games on the PS2 and later, I got no PS games that I wanted to play.
I have no idea how to answer your question anyway. So what if the emulator only has compatibility with 80% of worldwide titles? Would you play the titles that it cannot play perfectly? What would you do, if
no emulator has compatibility with 100% of games? I doubt such a perfect emulator exists anyway; even if it's good, it's impossible for all games to have surely no bugs that could cause problems when the environment changes.
I never saw ELF files related to the PS3 or XLF and XIN to the PS2.
Neither did I. I don't even know what "XIN" are.
But does it really matter? Why do you, as an end-user, care about the extensions? If I wrote software, I would care more about the file content, if I wanted a specific file. How I named my files, would be related to my project structure.
I won't buy another third-party component cable because I don't want to have the
flickering problem I do when playing PS2 games.
You're somehow either doing something wrong or just unfortunate to get the combination of equipment that results in such an experience. :/
Where can I find GSM on POPStarter, by the way?
Why not just use GSM itself, when the software doesn't have it integrated?
GSM was integrated into OPL to:
1. Give the user greater convenience.
2. Improve the user's experience. Since PS2 games are made to control the whole PS2, the game must support the video mode's resolution and characteristics. So the video mode setting for GSM could become game-specific. But yet, you cannot really have game-specific profiles if GSM remains a standalone program that you run before OPL.
What are the advantages of the component cable vs. the PS2 to HDMI Converter?
The PS2's Multi AV Port offers only analog video signals. So I suppose having a HDMI adaptor would:
1. Aid the case where the TV doesn't support 240P - but this also depend on whether the adaptor does.
2. Help you save 1 component input.
3. Help you, if the upscaling of your TV is somehow worse than what the HDMI adaptor could do.