UA6527/UA6527P - music sound diffrent on those two CPU chips

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krzysiobal
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UA6527/UA6527P - music sound diffrent on those two CPU chips

Post by krzysiobal » Tue Nov 26, 2013 2:34 pm

UA6527P is the name of IC that acts like a CPU in many famiclones.
I bought also UA6527 which is very rare. I recorded music from two games on those chips (on the same game console, with 26.601712 MHz crystal). First game is Duck Tales II, the second one is Doki Doki Yuuenchi. The music is very different on those chips. Can someone give reason? Is it because of diffrent duty cycles?

http://krzysiobal.fm.interia.pl/famiclone/ua6527.mp3
http://krzysiobal.fm.interia.pl/famiclone/ua6527p.mp3

tepples
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Re: UA6527/UA6527P - music sound diffrent on those two CPU c

Post by tepples » Tue Nov 26, 2013 2:49 pm

For comparison, this is what DuckTales 2's prologue sounds like on an NES. The only Doki Doki I know is Panic, so I can't help you there.

The 6527 recording of DT2 differs in these ways:
  • As in several other inaccurate famiclones, bits 7 and 6 of ports $4000 and $4004 have been swapped, causing the timbre of pulse waves to be wrong.
  • The crystal is somehow getting divided by 12 (like NTSC NES) instead of 15 (like Dendy) or 16 (like PAL NES) before being fed to the APU, causing the pitch to be too high.
  • Tempo is slow due to the music engine getting called at 50 Hz (like Dendy or PAL NES) instead of 60 Hz (like Famicom, NTSC NES, and PlayChoice).
The 6527p (p for PAL?) corrects the pitch problem but appears to have a missing bit in the volume registers.

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blargg
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Re: UA6527/UA6527P - music sound diffrent on those two CPU c

Post by blargg » Tue Nov 26, 2013 2:50 pm

Behind the awful overmodulation distortion, the second (p) one is at a lower key, though it sounds like you're playing different music. The volume levels also sound less linear, such that lower channel volumes are more faded out than the first.

krzysiobal
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Re: UA6527/UA6527P - music sound diffrent on those two CPU c

Post by krzysiobal » Sat Nov 30, 2013 7:18 pm

I find out that some games played on this cpu behaves weird - for example Micro Machines has graphical glitches on the title screen and during hero selecting (similar to those on emulator when pal mode is set).

Some games from Codemaster's Pegasus Golden Five (Fantastic Adventures of Dizzy) hangs after CodeMasters Logo.

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l_oliveira
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Re: UA6527/UA6527P - music sound diffrent on those two CPU c

Post by l_oliveira » Sat Dec 07, 2013 6:22 pm

UA6527 is for 21.47727Mhz crystal (NTSC).
krzysiobal wrote:I find out that some games played on this cpu behaves weird - for example Micro Machines has graphical glitches on the title screen and during hero selecting (similar to those on emulator when pal mode is set).

Some games from Codemaster's Pegasus Golden Five (Fantastic Adventures of Dizzy) hangs after CodeMasters Logo.
Of course, you're overclocking it. It's glitching.

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