[FR] Mult-Disc games - Swap in memory

[Dimensional]

I've been looking around, carefully even, to see if there is comments about this, or if there was a request already made in here.

There are some games, very few in fact, that use multiple discs. While rebooting the PS2 to switch discs is currently the only feature, being able to swap between the discs, be in USB or HDD, would be helpful for some games that use seamless swapping, like having menus that pause and wait for a disc to load. It would speed things up, and some games, like Monster Rancher, incorporate other discs into their game mechanics.

At the very least, this could be used to swap between the multiple discs for a single game, ie Xenosaga 2/3, as those are simpler with a set number of discs that have a known ID and potentially location on the USB or HDD.

[aphirst]

This would be an interesting feature. If it weren't for Monster Rancher, my recommendation would be something along the lines of what Nintendont / Devolution / Nintendont do for GameCube games (on the Wii / Wii U):

• Store the discs together (those tools expect a folder Game Name [IDCODE] and with the files game.ext and disc2.ext)
• Detect when the GameCube is on a "Insert Disc 1 / 2" screen (I think a certain flag is set by the game, maybe to stop the disc spinning?)
• When this occurs, toggle between the active discs, and give the game chance to recognise it

I'm not sure what exactly to recommend as a filename structure (or how this interacts with the data structure of games on a PS2 internal HDD), but it's possible that PS2 games similarly do something detectable when they request a disc change.

Monster Rancher, on the other hand, is probably a special case. From what I understand, the player temporarily swaps out the game disc for any other disc, and information from that disc is used in-game (monsters, items, whatever). Then, the player puts the original game disc back in, and play is resumed. The only reasonable way to handle this would be to have some way to, on the fly, toggle between [whatever medium the game is being loaded from] and [the actual DVD tray], hopefully being able to exploit similar game/drive-state flags like for GameCube games. However, I'm sure there are lots of pitfalls to making this kind of idea work.

Does anyone have a complete list of multi-disc titles, or which otherwise use the disc-drive in-game?

[Dimensional]

Here's a list of multi-disc PS2 games that is more or less complete. http://gaming.wikia.com/wiki/List_of_PlayStation_2_video_games_with_multiple_discs

For these games, I'd say incorporate into the loader a set list of known games, or allow the creation of text files that OPL reads and loads into memory, like an INI file with [headers] for each game, and every disc ID and partition ID grouped under each of those headers. Something a little similar to POPSLoader's discs.txt function. Since using an internal HDD uses the PS2 Partition scheme, that means every game should have a pre-made partition header/name. Why not use something like that to determine games? When the swap command from a PS2 game activates, if the game is a known multi-disc game, it could swap partitions on the fly, but give a wait time to properly emulate the disc swap function and decrease chances of bugs.

As for Monster Rancher, it's true that it pauses game play to wait and read a disc ID. That means it can't use the current method of disc swapping at all. I would believe a special patch would have to be included into OPL for these types of games that instead has it read either a random partition on the drive and inject the game's header data into the read area for the game. That, or find some way to manually select a game on the HDD or DVD Drive, through hotkeys or a menu patch, similar to how some NDS flashcarts create menus while in came. Could also potentially use the same INI concept to create a list of a disc partitions it would read from.

Since I am no where near as skilled in programming to do this myself, I can only suggest ideas. However I know a just enough to figure if something is potentially feasible, and something like this is, but would require more memory management than what it currently has.

[TnA-Plastic]

Which of those games do not have a Save-Point between disc-change?

If there are none: Is this really an 'issue' or rather an 'inconvenience'?

...an 'IGM' (In-game-menu) would be NICE (where you can IGR, or disc-change and other things). ^^

[Dimensional]

It's not just that, but some games incorporate disc switching as the key function, like Monster Rancher. The game keeps some basic code in memory, like the current screen, as well as executing some disc ID reading, so it can temporarily allow you to swap discs. As for if it's an issue or inconvenience, I'd say it's more of the latter than the former, but having some IGM regardless would be helpful. Even something to allow games like MR to read actual discs, or even read the partition header of another game, emulating the Disc ID.

[SeongGino]

Which of those games do not have a Save-Point between disc-change?

If there are none: Is this really an 'issue' or rather an 'inconvenience'?

Surprised no one has brought these up; The Dynasty Warriors Xtreme Legends expansions (applies to 3, 4, and 5) have some integral additions to the core game - characters, weapons, stages, story - but requires actively swapping in that XL game's vanilla companion to 'load' (or more accurately, unlocks - the XL and vanilla data are all on the same disc, as one would expect) original data, so one could play the original game, but with additions like custom parties or the fifth/ultimate weapons. One needs to have Xtreme Legends to experience both it, and its base games', content to the fullest, so working disc swap functionality is a necessity (otherwise, you'd intentionally be gimping yourself).

There's also the PS2 version of Dragon Ball Z - Budokai Tenkaichi 3, which uses disc swap to allow the extra modes from Tenkaichi's 1 and/or 2 to be played in 3 - and seeing as, like DW:XL, Tenkaichi 3 has a mundo expanded roster and other updates over its predecessors, having the functionality work would be nice to experience the game (or in this case, its bonus content) as it was originally intended.

If I was to make a completely hypothetical suggestion, perhaps having the ability to 'queue' game slots before loading, start the first disc, and then use a hotkey to switch to the next one in the cycle, would be a way of having it work in the most basic, two-disc scenario. If I recall, this is how the Dreamcast's (technically extra hardware, but working via software) USB GD-ROM works - or, maybe follow the GD-EMU's example; if the partitions are organized in a sane alphabetized way (or in a user-formatted logical manner, in which a game is followed up by its paired disc counterpart), a similar hotkey would simply tab over to whatever game partition follows - it's fair to assume that "Disc 1" comes immediately before "Disc 2" in a typical scenario, but it could probably only work on hard drives. As for Monster Rancher, and whatever else uses disc info as a simple checksum/whatever routine for runtime generated events, it might be better to assume the user at least has some discs laying around to use in those cases - the methods I previously suggested could be done without a HUD on behalf of OPL, but generating an IGM would be a substantially bigger ask.