Ys Book II Bug?

[C-R-T]

Hey guys.

Playing Ys Book II currently. Got to the first boss in the caves, and it insta-kills me with a single hit. A guide I found says you're supposed to lose 20 HP per hit, at level 37. I am at level 41, and lose 166+ (max) HP. I have small sheild and chain armor equipped, the best gear you can reasonably get at this point in the game.

This does not happen on real hardware. Mister core issue? Anti cheat mechanism in the game (cheats are not enabled)? My Mister is fully up to date with update-all and I have a fully working 128 MB memory module.

I managed to beat the boss, but I obviously had to do it without getting hit even once. We'll see what happens on the next boss battle.

[Lightwave]

Is this with an unmodified Redump image?

Also, which region? I know you said this doesn't happen on real hardware, but there were difficulty changes made between the Japanese and North American releases:

https://tcrf.net/Ys:_Book_I_%26_II#Book_II

[C-R-T]

Unmodified redump, north american version.

[dshadoff]

I haven’t played this in many years, but it sounds like you don’t have “something” you are expected to have at this point. It would be very weird for a core issue to have such a subtle effect on an individual game though.

If you have a save game from before entering the cave, I can try it on my own hardware/software, and see if there is any different behaviour between MiSTer and real hardware.

[C-R-T]

Sorry, I immediately over wrote the save file the moment I beat the boss. Like I said before, I was pretty over leveled and had the reasonably affordable equpment at the time in the game, and yet got killed in one hit. I've now progressed towards the end of the game and nothing strange so far - all bosses have been behaving.

It's funny, back when I first played Ys 1-2 Complete, almost 20 years ago, it was hard to find hints and info for that version of the game. Now the situation is reversed! All guides have been updated to be for the Ys Complete version, and the Turbo specific guides are gone. They're similar games but not quite the same!

[12characters]

I played this part of the game the other day and easily beat the first boss using fire magic. Perhaps you missed picking up the relevant magic staff before battle.

[C-R-T]

No, I had it. The fire magic is mandatory for the boss battle. Did you die of a single hit too?

[12characters]

No, I had it. The fire magic is mandatory for the boss battle. Did you die of a single hit too?

I only remember that the fight was quick and easy. Perhaps the cleria ring protected me. Did you find that item and enable it?

[C-R-T]

No, I had it. The fire magic is mandatory for the boss battle. Did you die of a single hit too?

I only remember that the fight was quick and easy. Perhaps the cleria ring protected me. Did you find that item and enable it?

Yes. And I agree that the fight was quick and easy, but one hit kills still aren’t normal.

[dshadoff]

Yes, true, unless you are "missing something important". If there were a save file to test with, it could be brought to real hardware to confirm; as it is, it will need to wait for somebody to reach that point to first confirm the same experience as you, and then try to obtain a save file for testing purposes.

[paulbnl]

The SNES core had a similar issue with a Beavis and Butthead game which was caused by wrong behavior when adding/subtracting invalid
numbers (non-decimal) in decimal mode.
https://github.com/MiSTer-devel/SNES_MiSTer/issues/261

The TurboGrafx core doesn't have that fix yet.
https://github.com/MiSTer-devel/SNES_Mi ... r.vhd#L118
https://github.com/MiSTer-devel/TurboGr ... D.vhd#L119

According to this doc the 65C02 and 65816 differ in behavior with the SBC opcode but ADC should be the same. http://www.6502.org/tutorials/decimal_mode.html#A

It would be good if this behavior can be verified on hardware using test roms.

[dshadoff]

According to this doc the 65C02 and 65816 differ in behavior with the SBC opcode but ADC should be the same. http://www.6502.org/tutorials/decimal_mode.html#A

It would be good if this behavior can be verified on hardware using test roms.

...And the HuC6280 is different as well on various points of 6502-ness.

But your point about running tests to be certain is certainly something we should do in order to confirm proper operation.
Do you have any assembly source to point to which performs such a test ? Only the core portion of the computation is important, as all the system setup and display would need to be custom for PC Engine.

[paulbnl]

The same doc contains a program to verify decimal mode operation.

http://www.6502.org/tutorials/decimal_mode.html#B

Errata
http://www.6502.org/tutorials/decimal_mode.html#D

[M.Walrus]

I played through ys book 2 a couple times already in the most recent tgfx core and did not encounter this issue. It could be a game bug depending on the equipment gathered when encountering the boss. It would be hard to try and reproduce without knowing specifics of your level + inventory with a save file preferably