Overclocked

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Angel
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Overclocked

Post by Angel » Thu Jan 17, 2013 10:39 am

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Hi all!

The uzebox Overclocked to 28.61818Mhz, would it be possible to increase the speed? How high? Could we extend the graphical resolution to this?

Thank you very much for the answers

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Janka
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Re: Overclocked

Post by Janka » Thu Jan 17, 2013 3:51 pm

Angel wrote:The uzebox Overclocked to 28.61818Mhz, would it be possible to increase the speed?
The clock rate has to be a integer multiple of exactly 3.579545 MHz, otherwise the NTSC color coding won't work (with RGB output, this restriction is nil).
So the current clock rate is 28.63636 MHz is 8 times that NTSC color burst frequency. The next integer multiples are at 32.215905 MHz and 35.79545 MHz, which is both nearly impossible to get a crystal for. So we'll had to use a PLL to synthezise these frequencies, which adds a lot of additional hardware and problems to the Uzebox.
How high? Could we extend the graphical resolution to this?
Uze has sure tested how high the overclocking works. I doubt it goes much higher than 35 MHz. The graphical resolution could be extended a little bit (e.g from 240 to 300 pixels in a row at 35.79545 MHz and mode 3).

tysonedriscoll
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Re: Overclocked

Post by tysonedriscoll » Thu Feb 07, 2013 3:48 pm

Janka wrote:The graphical resolution could be extended a little bit (e.g from 240 to 300 pixels in a row at 35.79545 MHz and mode 3).
Is it possible to extende graphical resolution more?

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D3thAdd3r
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Re: Overclocked

Post by D3thAdd3r » Thu Feb 07, 2013 11:16 pm

tysonedriscoll wrote:Is it possible to extende graphical resolution more?
It's already 143% of the 20mhz max speed specification, and not every '644 chip can even do the uzebox rate of 28.636. Whatever small percent of over-volted chips could do 35, get 1-2 extra cycles a pixel and still only have 4k ram to work with...so it wouldn't be a super nintendo/famicom all of a sudden :|

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