06494: thndrbld, thndrbld1, thndrbldd: Objects momentarily disappear

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
06494	Graphics	Minor	Always	Feb 4, 2017, 15:24	Apr 7, 2023, 16:19

Tester	Yonah	View Status	Public	Platform	MAME (Official Binary)
Assigned To		Resolution	Open	OS	Windows Vista/7/8 (64-bit)
Status [?]	Confirmed			Driver	sega/segaxbd.cpp
Version	0.182	Fixed in Version		Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	06494: thndrbld, thndrbld1, thndrbldd: Objects momentarily disappear
Description	At certain times during the demo and gameplay, all of the objects on screen (buildings, trees, enemies, bullets, player's helicopter) will disappear for a single frame. This can be easily observed at 35 seconds into the game's demo mode. In a 5 second span there are 4 times when all of the objects disappear for a single frame, leaving only the background. Possibly not a bug with MAME but with the original hardware.
Steps To Reproduce
Additional Information	If the SUBCPU is underclocked to 90%, the problem becomes more severe. If overclocked to 110%, the problem is resolved.
Github Commit

Flags
Regression Version
Affected Sets / Systems	thndrbld, thndrbld1, thndrbldd

Attached Files	0000.png (76,624 bytes) Feb 4, 2017, 15:24 Uploaded by Yonah

No.13594 B2K24 Senior Tester Feb 6, 2017, 05:59	I'll confirm this for now as I see the exact same thing as your snap shot when creating an AVI with MAME and cycling through it frame by frame with MPC-HC.
No.21289 Cow Tester Apr 7, 2023, 16:19 edited on: Apr 7, 2023, 16:21	Could possibly be that the SUBCPU's clock speed is wrong in MAME. Its more noticable in the Upright set than in the Cockpit/Deluxe revision. If anyone's got a good capture of a PCB, it would be greatly appreciated.