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First post, by NewRisingSun

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FixMPU is a software solution for the "hanging note bug" encountered when using the MPU-401 interface of Sound Blaster 16 cards bearing DSP versions greater then 4.05 and smaller than 4.16. Refer to this wiki article ("Type 1" only) for a more detailed description.

FixMPU acts as a launcher for the actual game. Instead of typing "DOOM" at the command line, type "FixMPU DOOM", followed by any command line parameters. The BLASTER= environment variable must be correct in the the A, I and P values. Only IRQs below 8. On two tested systems with affected Sound Blaster 16 cards, FixMPU successfully prevented the well-known high-pitched garbage notes from occurring. FixMPU does not attempt to correct any other hardware or software problem, such as slow-downs or missing MIDI messages as a result of games' short delay loops (hello LucasArts and Sierra).

Please refer to the included FIXMPU.TXT for technical details. Source code included. Comments welcome, but only to this thread, not via PM.

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Reply 1 of 6, by darry

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NewRisingSun wrote on 2020-10-31, 14:41:

FixMPU is a software solution for the "hanging note bug" encountered when using the MPU-401 interface of Sound Blaster 16 cards bearing DSP versions greater then 4.05 and smaller than 4.16. Refer to this wiki article ("Type 1" only) for a more detailed description.

FixMPU acts as a launcher for the actual game. Instead of typing "DOOM" at the command line, type "FixMPU DOOM", followed by any command line parameters. The BLASTER= environment variable must be correct in the the A, I and P values. Only IRQs below 8. On two tested systems with affected Sound Blaster 16 cards, FixMPU successfully prevented the well-known high-pitched garbage notes from occurring. FixMPU does not attempt to correct any other hardware or software problem, such as slow-downs or missing MIDI messages as a result of games' short delay loops (hello LucasArts and Sierra).

Please refer to the included FIXMPU.TXT for technical details. Source code included. Comments welcome, but only to this thread, not via PM.

This is very interesting and useful . Thank you very much for sharing .

Reply 5 of 6, by vetz

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Amazing work! Will test it out 😀

Wish this came 10 years ago, then my collection/system setup would've looked very different.

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Reply 6 of 6, by EmpireOfScrap

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This is quite amazing work. Thank you also for explaining the theory of operation and providing the source code in the archive.

I have tried this out with two cards yesterday and it worked fine out of the box! I will do more testing later, but reading on how it works, I assume it will work the same on all the cards.