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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
08715 Speed Minor Always Jul 9, 2023, 21:54 Jul 11, 2023, 09:48
Tester BIOS-D View Status Public Platform MAME (Official Binary)
Assigned To hap Resolution Fixed OS Windows Vista/7/8 (64-bit)
Status [?] Resolved Driver
Version 0.256 Fixed in Version 0.257 Build 64-bit
Fixed in Git Commit 9db3fe8 Github Pull Request #
Summary 08715: vclock3: [possible] Clock runs slower, it needs around 78 seconds to reach a minute
Description Clock runs slower than real time clock. Only tried so far on a laptop with fixed 60Hz resolution. I already described the bug here, but I am also learning how the platform works. I apologize beforehand if I commit some error:
Steps To Reproduce Run vclock3 using default settings and use a chronometer as soon as program starts. It's optional to set time or input anything to remove blinking LEDs. Minute updates aproximately every 78-79 seconds.
Additional Information Activating cheats and overclocking main CPU to around 115% aproximates a real behavior.
Github Commit
Flags Possible
Regression Version
Affected Sets / Systems vclock3
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Senior Tester
Jul 10, 2023, 02:57
Does this change fix it?
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Jul 10, 2023, 19:48
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Jul 11, 2023, 08:50
edited on: Jul 12, 2023, 21:12
Thank you so much for looking into this. I should have looked at the commit list before posting the bug here. I think for the most part this fixes it. Right now I'm running a 24 hour test with the fix using "mame vclock3 -priority 1" and AC Frecuency set to 60Hz. I'll do the same with AC Frecuency set to 50Hz after.

I'm not sure how accurate the real hardware is, but so far I have 12 hours on the test and from 12:00 AM to 12:00 PM my smartphone chronometer tells me emulation took 12 hours and 16 seconds. A bit off,, but a lot better than before.

I'll add a new note (or edit this one if possible) with the complete test for both configurations, just in case it gets useful.

EDIT: "mame vclock3 -priority 1" returned "Average speed: 99.99% (86747 seconds)" and it took 24 hours and 18 seconds to reach a full 12:00 AM cycle. Notice I only measured 86,418 seconds from it and second half only went off by only 2 seconds more. The fix was successful, thank you very much.

EDIT2: "mame vclock3 -priority 1" with AC Frecuency set to 50Hz returned "Average speed: 99.99% (86491 seconds)" and it took 24 hours and 12 seconds. Up to 12:00 PM it was off by only 3 seconds. The timming for both main CPU configurations are right. It's emulation from my end that had hiccups and made the timming off.
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Jul 11, 2023, 09:48
For 50hz, it expects a lower cpu freq, see the note I added in that commit.