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ID Category Severity Reproducibility Date Submitted Last Update
0000002 [ParaJVE] Emulation > Sound major always 2008-12-01 13:33 2008-12-03 13:22
Reporter parabellum View Status public  
Assigned To parabellum
Priority normal Resolution fixed  
Status resolved   Product Version Release 0.6.0
Summary 0000002: No sound in Star Hawk
Description The emulation does not emit any sound when playing Star Hawk, although the
game intro music is played correctly. Depending on the system load, some
noise can be heard from time to time when playing the game.
Additional Information It is a regression that appeared in version 0.4.0 (the sound was working perfectly in release version 0.3.2).
Tags Sound
Cartridge Star Hawk
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(0000005)
parabellum (administrator)
2008-12-03 13:22
edited on: 2008-12-03 13:23

 The bug was caused by the write to DAC output feature, introduced in version 0.3.2 : in my original implementation, whenever the CPU was writing directly to the sound output line, the sound generated by the AY38912 chip was discarded.

This was not a problem for games like Spike (where no sound is emitted by the AY38912 while Spike is speaking), but it does matter for Star Hawk, as this game makes the CPU send a continuous sinewave signal on the sound output line. I'm not sure why Star Hawk does this, as the wave amplitude is too low to be heard ; but anyway it was enough to let ParaJVE disable the sound emitted by the AY38912 chip.

To fix this issue, ParaJVE now merges the output emitted by the CPU and the AY38912 (so that both signals can be heard at the same time).

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