Terminator 2 - Judgment Day on Game Gear

[Former user]

Original issue 371 created by ymhn9999 on 2014-01-26T23:52:34.000Z:

What is the expected output? What do you see instead?
The music in the intro is garbled, and there are graphical glitches in the first stage

What version of the emulator are you using (official, SVN revision,...)?
libretro version of r851 on Windows 8.1

[Former user]

Comment # 1 originally posted by ekeeke31 on 2014-01-27T09:45:33.000Z:

I do not see or hear anything wrong (Wii standalone port based on current SVN).

Can you post some screenshots which show the graphical glitches or be more descriptive about what you see /hear ? I am also not sure what intro you are exactly talking about, I just got a logo followed by title screen then the first level.

Also you might want to check the ROM you are using is not a bad dump.

[Former user]

Comment # 2 originally posted by ymhn9999 on 2014-01-28T05:48:25.000Z:

Ok, here are some screenshots of what I am talking about:

http://imgur.com/yaL0PaH,jVgyQGNcomment 1.

Everything is fine in the first screenshot, but if you run around the stage for a bit, the ground and the top of the truck show the glitches seen in the second shot. The enemy sprites also flicker like crazy, but it was hard to capture this in a screenshot. I haven't played past this point to see if any other glitches happen.

The intro I am referring to occurs right after the Sega logo and the legal info screen. Music starts playing as it shows the T2 title screen. This is where the music is garbled; it sounds like static. It remains staticy as it transitions into the story scenes. The music in the first stage is fine, though. I tested 2 versions of the rom, including one from the NoIntro set, in both Fusion and TwoMBit, and they worked fine. Perhaps this is a libretro issue.

[Former user]

Comment # 3 originally posted by ekeeke31 on 2014-01-28T07:48:29.000Z:

Ok, we were not talking about the same game. I will have a look at this one when i got some time.

[Former user]

Comment # 4 originally posted by ekeeke31 on 2014-01-28T11:52:11.000Z:

[Former user]

Comment # 5 originally posted by ekeeke31 on 2014-01-29T09:33:58.000Z:

It seems like it somehow got broken between 1.6.0 (SVN r633) and 1.7.0 (SVN r683)

If you got some time and know how to compile from SVN, you can help me trying to figure what caused these bugs by testing revisions between those two and tell me which one started to exhibit those problems (note that sound and graphic glitches could be separated issues and could have been introduced at different points, i am not sure).

No need to test all revisions, only those containing changes related to the core (Wiki updates or platform port specific changes can be ignored)

[Former user]

Comment # 6 originally posted by ymhn9999 on 2014-01-30T08:22:11.000Z:

Ok, I'll see what I can do to help.

[Former user]

Comment # 7 originally posted by ekeeke31 on 2014-01-30T13:23:24.000Z:

Well, don't bother, I figured this one, it will be fixed in an upcoming commit.

For personal record:
It's actually caused by a bug in the game. The program enables raster line interrupts but never initializes VDP register 10 which normally sets the interrupt interval, so the interrupt occurs every line (this register is resetted to zero on power-on) which makes the game go in panic mode (sound and graphics issues).

It could be that this register is set to $FF on a real Game Gear at power-on, which actually makes the line interrupts never occuring (and fixes soudn & graphic issues on that game) but without any hardware to test on, it's only a guess.

[Former user]

Comment # 8 originally posted by ekeeke31 on 2014-03-02T15:47:58.000Z:

fixed in r852