Thread: Amix in WinUAE
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Old 22 May 2013, 17:24   #45
Toni Wilen
WinUAE developer
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 44
Posts: 23,136
I debugged it more and above update isn't the problem. It hangs because KS ROM uses CIAB alarm interrupt for timing stuff but Amix does not disable it early enough after taking over the system.

After system has been taking over, alarm interrupt will trigger in 13 frames (due to CIA TOD bug) and hangs the system because at this point Amix level 6 interrupt handler does nothing. (Clears INTREQ but does not read CIABICR)

I noticed these hangs randomly during 2.6.0 betas but reseting and trying again usually "fixed" it. Then later changes that moved SCSI and IDE to separate thread changed timing too much and broke Amix completely.

This image shouldn't work on real hardware either unless this HDF has different loader or buggy version or something..

Or perhaps there are CIA chips that don't have TOD bug but at least my A500 has exact same 8520A-1 label as my A3000 and A500 CIA does have the bug. (Non-buggy versions are also highly unlikely because surface mount version and Akiko internal CIAs are also confirmed to have same TOD bug)

CIA TOD bug =
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