[Oberon] XGA frequency in FPGA Oberon

Magnus Karlsson magnus at saanlima.com
Wed Dec 18 01:53:03 CET 2019

See http://tinyvga.com/vga-timing/1024x768@70Hz

My guess is that with 25 MHz CPU clock it's a lot easier to generate 75 
MHz than 65 MHz.


On 12/17/2019 4:31 PM, Skulski, Wojciech wrote:
> All:
> we have been playing with the FPGA Oberon firmware and we are puzzled with the peculiar 75 MHz frequency driving the display in Pepino. It actually works with the monitor which we have. People are saying on the web that XGA clock is 65 MHz. See http://tinyvga.com/vga-timing/1024x768@60Hz
> NW in his PO.Computer says on page 19 that the frequency should be 56 MHz, rounded up to 60 MHz. So all these numbers are different, 56, 60, 65, and 75 MHz. Does anyone know why? And which one is right?
> Thank you,
> Wojtek
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