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Old 21 July 2015, 16:30   #83
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Join Date: Jun 2010
Location: NL/PL
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Originally Posted by Staringlizard View Post
Unfortunately, after some testing and tweaking I think 720p is the limit for this hardware. The reason for stretching out the screen is not just to fill up empty space, it is simply because I do not have the time to both read and write from/to 8ns sram at the speed required (74.25Mhz reading and 28Mhz/14Mhz writing). The solution is to read pixels from sram at half rate (e.g. display each pixel twice), then I get a very manageable total maximum speed of 65,125Mhz read/write. Perhaps we will revisit the schematics and come up with something faster, still keeping the price tag down.

Just buffer/interleave R/W - should be fine - 8ns access is way above 100MHz so with proper cycling You should be able to fit in this perfectly.

And yes - output easily can be pixel doubling/quadrupling + max size is not full 1920 line period and as such you can use part of time for other thing (and mask with fixed color) - it will create some pilarbox but i believe this is unavoidable if you think about pixel perfect Amiga screen replication on modern 16:9 FHD TV's (pilarbox can be removed in TV when this mode will be selected and trough correct signaling and usually TV will provide better scaler than FPGA can have without going to expensive one, also you can use own timing but it is different case).

Last edited by pandy71; 21 July 2015 at 16:35.
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