08446: famicom [famijmp2]: Does not start (grey screen)

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
08446	Misc.	Major	Always	Oct 18, 2022, 19:41	Oct 20, 2022, 11:22

Tester	Firewave	View Status	Public	Platform	MAME (Official Binary)
Assigned To	kmg	Resolution	Fixed	OS	Windows 10/11 (64-bit)
Status [?]	Resolved			Driver	nintendo/nes.cpp
Version	0.248	Fixed in Version	0.249	Build	64-bit
		Fixed in Git Commit	05b04a4	Github Pull Request #	#10451

Summary	08446: famicom [famijmp2]: Does not start (grey screen)
Description	The sets does not start and only shows a grey screen.
Steps To Reproduce
Additional Information
Github Commit

Flags
Regression Version
Affected Sets / Systems	famicom [famijmp2]

Attached Files	0003.png (4,160 bytes) Oct 20, 2022, 02:10 Uploaded by Foxhack Screenshot from MAME 0.248 running the game

No.20633 Foxhack Tester Oct 20, 2022, 02:08	It -does- kinda work. If you load the game the first time, you only get a gray screen. But if you press F3 (to reset), the game boots. It looks like the game doesn't start at first because it's missing its battery backed NVRam data. So if you load the game and it doesn't find anything, it just hangs. Once you reset, press Shift+F3 to force a power cycle, or close MAME and restart it, the game will boot normally since an NVRam file is created during any of those three situations.
No.20636 kmg Senior Tester Oct 20, 2022, 04:04	This one is a relative of the other Bandai games but without the EEPROM. I wonder why it needs reset? Somehow related to IRQ? It does look like the parent class function that writes the IRQ regs is overridden and so it has no working IRQ. That probably explains the broken effect on the title screen at least.
No.20637 Foxhack Tester Oct 20, 2022, 04:16 edited on: Oct 20, 2022, 04:19	I don't think that has anything to do with it, since resetting creates the battery backed memory that it's supposed to have. If it finds it empty, it probably assumes the backup battery is dead, and it won't boot. But since mame generates empty save data after running the game once, it works after you try it again. I tested this out by shutting off mame, deleting the memory, and starting the game again. Gray screen. Closed mame, loaded the game again, it works since there's a battery backup file now.
No.20641 kmg Senior Tester Oct 20, 2022, 06:56 edited on: Oct 20, 2022, 06:56	It seems this is a know problem: https://www.nesdev.org/wiki/INES_Mapper_153#Note There are several games that need this or that RAM to be not zero filled to run. Bad programming that depends on random uninitialized RAM contents. PR: https://github.com/mamedev/mame/pull/10451