Broken audio in Startropics 1 & 2

Discuss emulation of the Nintendo Entertainment System and Famicom.

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Zelex
Posts: 267
Joined: Fri Apr 29, 2011 9:44 pm

Broken audio in Startropics 1 & 2

Post by Zelex » Tue Jan 08, 2013 6:25 pm

I somehow broke audio in Startropics 1 and 2. I just get a weird, repeating, non-discernable noise. All other games work fine as far as I can tell. Do these games do anything special?

The rest of the game appears to work fine, just the audio is broken.

Zelex
Posts: 267
Joined: Fri Apr 29, 2011 9:44 pm

Re: Broken audio in Startropics 1 & 2

Post by Zelex » Tue Jan 08, 2013 7:32 pm

Noise is coming from the Noise channel. Go figure.

Typical APU writes are:

$10 = $00
$11 = $00
$17 = $40
$15 = $0f
$15 = $00
$11 = $50

This part repeated at the start of every frame and no other writes.
$15 = $00
$15 = $00
$15 = $08
$0c = $00
$0e = $01
$0f = $08
$15 = $08
$0c = $00
$0e = $01
$0f = $08
$15 = $00

Zelex
Posts: 267
Joined: Fri Apr 29, 2011 9:44 pm

Re: Broken audio in Startropics 1 & 2

Post by Zelex » Tue Jan 08, 2013 7:44 pm

Figured it out. It has something to do with disabling/enabling WRAM.

Zelex
Posts: 267
Joined: Fri Apr 29, 2011 9:44 pm

Re: Broken audio in Startropics 1 & 2

Post by Zelex » Tue Jan 08, 2013 7:50 pm

Docs say that it is not MMC3, but MMC6. That explains it. I'll hit this up later tonight.

Zelex
Posts: 267
Joined: Fri Apr 29, 2011 9:44 pm

Re: Broken audio in Startropics 1 & 2

Post by Zelex » Tue Jan 08, 2013 11:00 pm

fixed

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