00759: mtlchamp and clones: There is a problem with the nvram in the RAM / ROM check after you change some settings in service mode.

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
00759	Misc.	Major	Always	Feb 4, 2008, 12:26	Oct 11, 2017, 21:22

Tester	-Misc Reporters-	View Status	Public	Platform
Assigned To	MetalliC	Resolution	Fixed	OS
Status [?]	Resolved			Driver	konami/mystwarr.cpp
Version	0.99	Fixed in Version	0.191	Build
		Fixed in Git Commit		Github Pull Request #

Summary	00759: mtlchamp and clones: There is a problem with the nvram in the RAM / ROM check after you change some settings in service mode.
Description	Enter the service mode, and change a game option (Violence or Difficulty) then select 'Save and Quit', then 'Game Mode' to exit service mode. MAME will write 'mtlchamp.nv' to the 'nvram' directory. On the first reboot, the RAM / ROM check will fail. Thereafter, the check will succeed, but then 'Version Error' appears in the middle of the screen. The game will reset and this will continue in a loop.
Steps To Reproduce
Additional Information	Posted by marco75
Github Commit

Flags
Regression Version
Affected Sets / Systems	mtlchamp and clones

Attached Files

No.00546 couriersud Developer Apr 4, 2008, 08:55	Still reproduces in 0124u1 - How do I set the last repro version?
No.00547 Fujix Administrator Apr 4, 2008, 08:59	I have disabled editing the repro version field. Now it appears in the "update issue" page.
No.05964 Tafoid Administrator Apr 12, 2010, 17:26	Some discussion about this from Shimapong: http://www.mameworld.info/ubbthreads/showthreaded.php?Cat=&Number=219534
No.08373 NekoEd Senior Tester Mar 16, 2012, 14:15	This is still present, but the message board thread returns an error "We cannot proceed."
No.14198 MetalliC Developer Sep 30, 2017, 15:29 edited on: Sep 30, 2017, 16:02	short version: current emulation missing some interrupt disable logic, or this is caused by forced pull up logic in eepromser.cpp longer version: this game does not disable interrupts during EEPROM read when in test mode. interrupt handler write data to same port there connected eeprom and clear CS line in the middle of read cycle -> eepromser starts to output 1 data, so in result one (unused) byte of read data becomes FF, this lead to incorrect calculated checksum before data writeback.
No.14258 M.A.S.H. Senior Tester Oct 11, 2017, 21:22	Fixed by MetalliC: https://git.redump.net/mame/commit/?id=12b8cc98541c5e400ae9fc3a83215720cda40ca9