06901: snes [jdredd and clones]: Judge Dredd (all regions) stops working after title screen

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
06901	Crash/Freeze	Major	Always	Mar 6, 2018, 10:41	May 24, 2020, 01:02

Tester	Gryzor1363	View Status	Public	Platform	MAME (Unofficial Binary)
Assigned To	AmatCoder	Resolution	Fixed	OS	Windows Vista/7/8 (64-bit)
Status [?]	Resolved			Driver	nintendo/snes.cpp
Version	0.195	Fixed in Version	0.214	Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	06901: snes [jdredd and clones]: Judge Dredd (all regions) stops working after title screen
Description	Upon launching the game, emulation stops working after first title/copyrights opening screen.
Steps To Reproduce	Select SNES machine, then input game "Judge Dredd" as cartridge, wait for initial title screen to fade, then the persistent black-screen should occur every time. Issues is reproducible in all regions available (US, Europe, Japan).
Additional Information	Bugs observed using MameUI64 0.195 official build to launch systems / games. Noteworthy is that game worked from MAMEUI64 0.187 up until MAMEUI64 0.193 as per personal testing, albeit with video corruption in status info bar in the upper section of the screen. (colours corrupt/garbage on icons). Issue not initially reported since SNES driver has a "Video emulation is not 100% accurate" pop-up.
Github Commit

Flags
Regression Version	0.194
Affected Sets / Systems	snes [jdredd and clones]

Attached Files

No.16148 Gryzor1363 Tester Feb 15, 2019, 17:17	Behavior seems persistent after testing on latest MAMEUI64 0.206. Please also note that similar behavior has been found in Cliffhanger (All Versions). Title screen works, and then a black-screen prevents further actions. I will dedicate separate ticket for it if confirmed and required.
No.16149 Osso Moderator Feb 16, 2019, 09:05	The clock change in https://git.redump.net/mame/commit/?id=6b0f14ed7ba4eb854f4f9ff67112e88ef6589c74 caused the regression, while fixing a lot of other things, apparently.
No.16150 Gryzor1363 Tester Feb 16, 2019, 14:23	Thanks for the heads-up. So you confirm similar regression in both games are related to this root-cause ? should I raise a clone ticket for Cliffhanger in this case ?
No.16151 Osso Moderator Feb 16, 2019, 14:45	If they share the same regression, it's not necessary to open another bug report.
No.16153 Gryzor1363 Tester Feb 17, 2019, 12:56	Duly noted. AFAIK they share the same dysfonction, "symptomatically", while I do not know of previously working versions of MAME for this game prior to the regression.
No.16320 AmatCoder Tester Apr 10, 2019, 23:48	AFAIK, spc700 runs at 2048 Mhz but it has internal divider. This is the cause of the inconsistency between docs: The actual clock input is 2.048MHz but the effective clock rate is 1.024MHz.
No.16339 Gryzor1363 Tester Apr 18, 2019, 17:58	Thanks for the usual quality input AmatCoder. Any chance it can be fixed in the coming releases ?
No.16352 AmatCoder Tester Apr 21, 2019, 16:20	If you ask to me... I don't know. IMHO this would need revert the clock change (or apply the internal divider to cpu cycles). It will break "Rival Turf / Rushing Beat" again but I believe that it is an issue with 5A22 cpu master cycles. Moreover, I can confirm that "Cliffhanger" is broken by this issue (also "Taekwon-Do" and "Super Tekkyuu Fight!").
No.16912 AmatCoder Tester Sep 16, 2019, 14:12	I made a pull request for this issue: https://github.com/mamedev/mame/pull/5642 It fixes all games above-mentioned without breaking Rival Turf, Blackhawk etc. Also it fixes MT07419.
No.16940 Gryzor1363 Tester Sep 20, 2019, 15:34	Really ? Fantastic job AmatCoder, thanks for notifying.
No.16967 AmatCoder Tester Sep 25, 2019, 23:08	You are welcome. Also this commit fixes the score video corruption in Judge Dredd: https://github.com/mamedev/mame/commit/55bda8eb98feabf0c8b119503d9260b2e512c2e5 Unfortunately, it did not arrive in time for 0.214...:)
No.17671 Gryzor1363 Tester May 24, 2020, 01:02 edited on: May 24, 2020, 01:03	Stumbled upon your latest comment quite belatedly AmatCoder. Even though I doubt you'll ever have that notification, I wanted to extend my gratitude once more for that latest fix. Better late than never right ? Quite the joy to witness full compatibility of that game after so long struggling to find a suitable HLSL-capable emulator to handle it.