06896: krull: Mysterious deaths in Krull cave scene

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
06896	Gameplay	Minor	Sometimes	Mar 3, 2018, 16:18	Jun 25, 2020, 08:10

Tester	Dumple	View Status	Public	Platform	MAME (Official Binary)
Assigned To	dink	Resolution	Fixed	OS	Windows 10 (64-bit)
Status [?]	Resolved			Driver	gottlieb/gottlieb.cpp
Version	0.193	Fixed in Version	0.223	Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	06896: krull: Mysterious deaths in Krull cave scene
Description	I've been playing Krull via MAME and in the cave sequence (3rd stage), I suddenly die with no apparent cause. This happens once every three times or so. This recording shows a couple of examples, at 1:24 and 6:21 I tried searching and couldn't turn up any reports of this glitch. I haven't played the arcade PCB in 20+ years, so I'm not 100% sure this is an emulation issue.
Steps To Reproduce	I've attached a MAME 0.193 .inp file that triggers this twice (once at ~1:24 and once at ~6:21).
Additional Information
Github Commit

Flags
Regression Version
Affected Sets / Systems	krull

Attached Files	krull.inp (185,986 bytes) Mar 3, 2018, 16:18 Uploaded by Dumple
	krull_die.zip (4,305 bytes) Jun 23, 2020, 13:48 Uploaded by dink cave scene 0.220 state
	i86_neg_fix_dink_fbneo.zip (22,319 bytes) Jun 24, 2020, 14:13 Uploaded by dink i86_neg_fix_dink_fbneo.zip

No.14797 Tafoid Administrator Mar 3, 2018, 18:05	Thanks for the report and .inp file. I have to guess if it is anything, it is one of the Slayers about to spawn and it may check for a presence there. It seems to be in the same general area each time.. hard to say. We'll treat it as a bug until proven an actual bug in the game.
No.17766 dink Tester Jun 23, 2020, 13:43 edited on: Jun 23, 2020, 13:52	Did a little research on this one: the mysterious deaths are actually caused an enemy spawning which has a sprite that is not displayed. How I found out: play until the cave scene, hitting savestate every second (or so). When a bad death happens, reload the last state, and shoot in diff. directions until you hear a kill sound from the invisible enemy. state attached Debugger hints: watch 0x0DF1, this is increased right before enemy spawns. @ 0x1414, the game loops through a huge linked-list of sprites, which jumps around between diff. ram areas a lot (2xx, 3xx, 5xx, 7xx) This what I got so far, also - in mame 031's whatsnew, it says that [this?/a similar?] bug was fixed by an update to the i86 core, Unfortunately, so much was changed since 0.30 that I'm not sure what it could have been.. I wonder if the bug came back somehow over the years. Attached State file (krull_die.sta): fastforward to the cave scene in attract mode, then load this state. when you hear the enemy's laser blast, go Down+Right about 1cm, and you'll die from the invisible baddie.
No.17767 dink Tester Jun 24, 2020, 14:13	I found the problem, here's the fix, including info and references - see attachment: i86_neg_fix_dink_fbneo.zip