Terminator 2 - Judgment Day on Game Gear

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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

Original issue reported on code.google.com by ymhn9...@gmail.com on 26 Jan 2014 at 11:52

[GoogleCodeExporter]

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.

Original comment by ekeeke31@gmail.com on 27 Jan 2014 at 9:45

[GoogleCodeExporter]

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

http://imgur.com/yaL0PaH,jVgyQGN#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.

Original comment by ymhn9...@gmail.com on 28 Jan 2014 at 5:48

[GoogleCodeExporter]

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

Original comment by ekeeke31@gmail.com on 28 Jan 2014 at 7:48

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Original comment by ekeeke31@gmail.com on 28 Jan 2014 at 11:52

• Changed state: Accepted
• Added labels: CoreEmulation, Priority-Medium, Type-Defect

[GoogleCodeExporter]

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)

Original comment by ekeeke31@gmail.com on 29 Jan 2014 at 9:33

[GoogleCodeExporter]

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

Original comment by ymhn9...@gmail.com on 30 Jan 2014 at 8:22

[GoogleCodeExporter]

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.

Original comment by ekeeke31@gmail.com on 30 Jan 2014 at 1:23

• Changed state: Started

[GoogleCodeExporter]

fixed in r852

Original comment by ekeeke31@gmail.com on 2 Mar 2014 at 3:47

• Changed state: Verified