07309: invrvnge, invrvngegw: watchdog bites a few seconds after starting a game

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
07309	Crash/Freeze	Major	Always	May 1, 2019, 15:46	May 3, 2019, 02:56

Tester	Robbbert	View Status	Public	Platform	MAME (Self-compiled)
Assigned To	AJR	Resolution	Fixed	OS	Windows Vista/7/8 (64-bit)
Status [?]	Resolved			Driver	midw8080/8080bw.cpp
Version	0.209	Fixed in Version	0.210	Build	32-bit
		Fixed in Git Commit		Github Pull Request #

Summary	07309: invrvnge, invrvngegw: watchdog bites a few seconds after starting a game
Description	The watchdog kicks in a few seconds after starting a game.
Steps To Reproduce	Start machine. Press 5 Press 1 While the fuel meter is filling up, it seems to stutter a bit before freezing partway through. Watchdog bites, machine resets.
Additional Information	Tested with 32bit and 64bit. Happens on 0.208, but not on 0.206 Other clones work.
Github Commit

Flags
Regression Version	0.207
Affected Sets / Systems	invrvnge, invrvngegw

Attached Files

No.16398 Tafoid Administrator May 1, 2019, 19:28	Likely regression from this commit January 27, 2019: https://github.com/mamedev/mame/commit/e956008352c68af5e7457eb62561479a29da7b8e * mw8080bw.cpp, 8080bw.cpp: Interrupt modernization (nw)
No.16409 AJR Developer May 3, 2019, 00:00	This is due to a nasty scheduling bug that causes the value of m_screen->vpos() to occasionally be rolled back between the time the raster interrupt is generated and the time the interrupt is acknowledged, causing the mid-screen interrupt routine (RST 1) that resets the watchdog counter to be skipped repeatedly.
No.16410 AJR Developer May 3, 2019, 00:41	The fix may be ugly, but it's in. I'll keep this problem in mind when I return to my great 8080bw video rewrite.
No.16411 Robbbert Senior Tester May 3, 2019, 02:56	Thank you. :)