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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
07152 Sound Minor Always Nov 14, 2018, 20:33 Nov 16, 2018, 02:19
Tester vidpro1 View Status Public Platform MAME (Official Binary)
Assigned To Resolution Open OS Windows 10 (64-bit)
Status [?] Acknowledged Driver midtunit.cpp
Version 0.200 Fixed in Version Build 64-bit
Summary 07152: nbajam, nbajamte: NBAJAM unit sounds board DAC chip emulation acting funny, misfiring DAC 8 but samples such as snare are dropping out.
Description I believe I found this sound emulation bug by accident because I was muting the Yamaha YM2151 FM and all the OKI 6295 ADPCM sound channels. Just to inspect the drum track on these Nba Jam games and it is noticed on the 2nd Quarter tune and others. I saved a wav file with the DAC drum track only in Audacity and you can see the snare drum and some pieces of the drum track are dropping out. The DAC chip is not playing all the sounds completely and goes right to the next sample and randomly drops out when it wants to. I have used an old M1 sound emulator and this wasn't happening there. I will try and roll back to an older version of MAME and find one that doesn't have the problem.
I was trying to remix this tune and was trying to record the drum track, but I discovered it seemed like it was broken.
Not 100% sure if this is normal behavior I tried it on MAME .128 and it was doing it there too. I have a board my collection I should hook it up and try it.

UPDATE - if I use the MAME cheat engine and put the T unit main cpu to 1% to make the game freeze crash but the sound board is still running.
The Sound board DAC appears to play fine. I think the Main Williams PCB is sending requests through the ribbon cable to the 6809 sounds board cpu and that's probably where the issue is happening.
Steps To Reproduce
Additional Information
Regression Version
Affected Sets / Systems nbajam, nbajamte
Attached Files
mp3 file icon baddac.mp3 (296,612 bytes) Nov 14, 2018, 20:37 Uploaded by vidpro1
png file icon nbjamdac.png (84,922 bytes) Nov 14, 2018, 20:42 Uploaded by vidpro1
mp3 file icon nbjam2ndquarterperfectmusic-gooddac.mp3 (2,404,380 bytes) Nov 14, 2018, 20:43 Uploaded by vidpro1
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