05962: gotcha: Music suddenly stops

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
05962	Sound	Minor	Random	Jun 10, 2015, 16:33	Jun 11, 2015, 07:19

Tester	darq	View Status	Public	Platform	MAME (Self-compiled)
Assigned To		Resolution	Open	OS	Windows Vista/7/8 (64-bit)
Status [?]	Confirmed			Driver	misc/gotcha.cpp
Version	0.162	Fixed in Version		Build
		Fixed in Git Commit		Github Pull Request #

Summary	05962: gotcha: Music suddenly stops
Description	Music hangs at random points. Just play the game for a while, or press the fast forward key during a level. After a fast investigation, I found that the cause is the audio CPU NMI. I think that NMI is useless and also harmful. It causes 0xC00F reads (as noted in the source) and it expects an opcode there, so if you always return 0x00 = NOP instr. for example, the CPU reads/writes at 'strange' locations after a while. I also compared the audio CPU with silvmil that is a similar hw (PS: Isn't a good idea to merge gotcha with silvmil? ;)) and silvmil doesn't need an NMI.
Steps To Reproduce
Additional Information
Github Commit

Flags
Regression Version
Affected Sets / Systems	gotcha

Attached Files

No.11748 Tafoid Administrator Jun 10, 2015, 23:39	Confirmed the state of occasionally stalling music and not the reason listed above.
No.11750 darq Tester Jun 11, 2015, 05:25	Can I ask why you cannot confirm the NMI's fault? If my assumptions are wrong, I'd like to know why :-) Thanks.
No.11751 Mamesick Senior Tester Jun 11, 2015, 07:19	darq assumptions are right, 0xC00F location in the sound map should be enabled. Then there are two possibilities: 1) still mantain the NMIs and correctly emulate what happens there. 2) fill the location with AM_WRITENOP and then remove the NMIs from MACHINE_CONFIG since they are nested. (this is already done in the mentioned SILVMIL.C driver) I'm stunned that there's request and research of new contributors and still read answers like this.