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Old 11 April 2013, 10:49   #2033
Join Date: Jun 2010
Location: out in the wild
Posts: 1,243
Originally Posted by keropi View Post
the 49.500 pixel clock is missing from the list so I can't create a 75hz screen... clocks jump from ~42 to ~62 without any middle values.
Here's a clear statement - thanks for that. I'll introduce more pixelclocks in that gap with the next release. The PLL won't exactly reach the 49.5MHz, but on a PAL machine, you'll have 49.657MHz. I also noticed that the exact double of the Amiga pixel clock is missing from the list, so I'll add that as well. This will enable you to "manually" create a V-Synced output screen. The exact triple is already there (core A06).

@everyone: If there's an output pixel clock that you require to approach your desired output screenmode, just let me know, and I'll see if that's possible. You can calculate the possible pixel clocks with:


f is the resulting pixelclock in MHz
28.37516 may be replaced by 28.63636 in case of an NTSC machine
m is a whole-number multiplier between 1 and 32 (both including)
C is a whole-number divider between 1 and 18 (both including)

m and C make the filename extension of a core: C is an index to the alphabet, so you get a character between A and R. The the 2-digit number after that is the m-value.

The output pixel clock for 640x480 is very low at around 25MHz. I may have to re-calculate the PLL filter values in order to get that stable (i.e. get rid of temperature-dependency). The filter values are currently calculated for higher pixel clocks ranging from 40 to 135 MHz.

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