Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

PCE-CD Incompatibility - Mugen Senshi Valis - Legend of a Fantasm Soldier #554

Closed
zeromus opened this issue Jan 15, 2016 · 2 comments

Comments

Projects
None yet
3 participants
@zeromus
Copy link
Contributor

commented Jan 15, 2016

Mugen Senshi Valis - Legend of a Fantasm Soldier (梦幻战士妖子) PCE-CD can't run, it's just a black screen

@alyosha-tas

This comment has been minimized.

Copy link
Contributor

commented Nov 22, 2016

Leaving some notes on this as I try to resolve it.

The game is enterring a video mode where it is expecting an external VSYNC signal (and other control information) from the VEC. The fact that this is not happening seems to be masked by the emulator clamping number of scanlines and producing a VSYNC signal in the VDC regardless of what the display registers are otherwise indicating.

Ultimately the game receives no interrupts because the sytem to fire them is being confused by the video mode, so nothing happens after the intro sound track is loaded.

Relevent code : ExecFrame in VDC.Render.cs

@alyosha-tas

This comment has been minimized.

Copy link
Contributor

commented Jun 15, 2017

I tried debugging this again, but BizHawk's behaviour is not even close what is needed to make this game work.

The game expects to be able to execute a VBlank IRQ before a certain point in the code has executed. IN BizHawk the code is running way too fast, and executes a couple frames before the VBlank IRQ. The VBlank IRQ turns off VBlanks. The game expected the code (that already ran) to then turn them back on. Since this can never happen, the game is stuck.

Unless I'm missing something, I don't think this can be resolved with the current core.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.