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 Post subject: Overclock demo
PostPosted: Sat Mar 14, 2015 7:09 pm 
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Joined: Sun Sep 19, 2004 11:12 pm
Posts: 19257
Location: NE Indiana, USA (NTSC)
Do you like to overclock your NES? Run this ROM and see how far you're pushing the CPU. And if you've figured out how to change the clock while the power is on, be even more amazed.

This is part of the NES POST project.


EDIT: It has come to my attention that the way I'm figuring cycles per line has some systematic error due to FCEUX sucking at timing when the 9 sprites bit is activated. I have updated the ROM.


Attachments:
File comment: With corrected sprite 0 trigger horizontal position
oc-r1a.zip [24.41 KiB]
Downloaded 408 times
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 Post subject: Re: Overclock demo
PostPosted: Sat Mar 14, 2015 9:20 pm 
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Joined: Wed Jul 13, 2011 6:51 am
Posts: 395
Location: Brasilia, Brazil
Machine has a Brazilian M-PAL clone discrete PPU (same timing as NTSC but outputs color information in PAL standard), UM6548, clocked at 21.453666Mhz(3.575611Mhzx6).

@29.498928Mhz:
Image
Dendy-esque UMC CPU

Image
Legit RP2A03E


Using the legit RP2A03E CPU with the NTSC clock:
Image

With M-PAL clock:
Image


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 Post subject: Re: Overclock demo
PostPosted: Sun May 03, 2015 5:08 am 
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Joined: Sat Apr 18, 2009 4:36 am
Posts: 259
Location: Russia
Dendy (6527P/6538 chips):

Image

So, this old researches by HWM are confirmed again.


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