Viewing Issue Advanced Details
ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
01852 Graphics Minor Always May 31, 2008, 20:50 21 days ago
Tester Fujix View Status Public Platform MAME (Self-compiled)
Assigned To Resolution Open OS
Status [?] Confirmed Driver segas16a.cpp
Version 0.125u3 Fixed in Version Build C2D
Fixed in Git Commit Github Pull Request #
Summary 01852: fantzone, fantzone1: Graphical glitch of the background at the beginning of the game.
Description The background briefly gets corrupted when I start a game and get ready to play.
This is a long existing "one-frame" issue but clearly a bug and never seen on the real arcade.
Steps To Reproduce
Additional Information
Github Commit
Flags Verified with Original
Regression Version 0.88u7?
Affected Sets / Systems fantzone, fantzone1
Attached Files
gif file icon fanta.gif (165,717 bytes) May 31, 2008, 20:53
Relationships
related to 08065Resolvedhap  altbeast, altbeast6: Random graphics flickering 
Notes
5
User avatar
No.09127
moa
Tester
Dec 8, 2012, 22:29
looks fixed in 147u2
User avatar
No.09134
Tafoid
Administrator
Dec 13, 2012, 23:45
Still happens here, tested with 0.147u3. You really can see if it you SHIFT+P (pause by frame) your way to it.
User avatar
No.09143
Phil Bennett
Developer
Dec 18, 2012, 15:56
What's happening is the MSBs of the scroll registers are being overwritten mid-frame when the round starts by a routine which clears the text RAM (the scroll registers occupy the last few words of the RAM). The correct scroll values are restored during the following VBLANK.

Adding VIDEO_UPDATE_AFTER_VBLANK will hide the glitch.
User avatar
No.19222
hap
Developer
21 days ago
It is just this single-frame glitch? Then VIDEO_UPDATE_AFTER_VBLANK (or an other hacky workaround) is not worth it.
User avatar
No.19223
Haze
Senior Tester
21 days ago
yeah, as I previously speculated I think maybe the hardware latches these scroll values at some point, but doing that was shot down when I suggested it.