05387: nibbler: Some animations run too fast.

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
05387	Timing	Minor	Always	Dec 2, 2013, 00:52	Nov 26, 2019, 16:17

Tester	Zaphod	View Status	Public	Platform	MAME (Official Binary)
Assigned To	AJR	Resolution	Fixed	OS	Windows Vista/7/8 (64-bit)
Status [?]	Resolved			Driver	snk/snk6502.cpp
Version	0.151	Fixed in Version	0.217	Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	05387: nibbler: Some animations run too fast.
Description	The snake warping in animation runs too fast, causing it to finish before the triple sweep does. On real hardware, it syncs precisely with the sound effect. This is confirmed on video from real boards on youtube. this has been present for a LONG time.
Steps To Reproduce	Just start a game. Happens every single time.
Additional Information	Incidentally, some real boards suffer from this same timing error. The speed of actual gameplay is probably correct. I believe similar issues exist with fantasy, because the timing of the ending seems off to me, but i cannot confirm this. but i'm pretty sure it's a general fault in the driver.
Github Commit

Flags	Verified with Original
Regression Version
Affected Sets / Systems	nibbler

Attached Files

No.10042 Tafoid Administrator Dec 2, 2013, 14:46	I have a fix for this in 0.152 (r26289) by changing the clock rate down to adjust for the issue - but I'm told my divisor is wrong. So, it's not fixed but feels closer. It will need to be reexamined.
No.15908 MetalGod Senior Tester Dec 13, 2018, 23:10	This was fixed in mame 0.152: -snk6502.c: Adjusted Nibbler board clock rate to use actual known master clock and a logical divisor. [Tafoid]
No.15921 NekoEd Senior Tester Dec 18, 2018, 06:10	Tafoid stated the divisor is not confirmed, so until we know what it is for certain, this remains open.
No.17214 AJR Developer Nov 26, 2019, 16:17	I've confirmed the actual CPU clock divider from schematics. It's 11.289 MHz divided by 8, but the wait states imposed on most ROM reads effectively cut that frequency in half most of the time. This applies to all games in snk6502.cpp but the earliest ones, which run with a CPU clock divider of 16 and no wait states.