[Coco] Rgb2vga improvements

[Luis Antoniosi (CoCoDemus)]

The flickering pixels are only visible in white or pure black. I will make
some tests but I believe the problem is in the input and not the output. It
could also be the RAM since I use two lines in RAM to store the
incoming/outgoing lines before/after they are wrote/read to/from the SDRAM.

I have a TSOP-II 512K SRAM that I need to solder to test, but if the
problem is the RAM i still will have the same problem. Maybe I should
change the way the RAM is accessed.

Luis Felipe Antoniosi




On Tue, Sep 16, 2014 at 1:00 PM, Steven Hirsch <snhirsch at gmail.com> wrote:

> On Tue, 16 Sep 2014, Luis Antoniosi (CoCoDemus) wrote:
>
>  Yep you could definitely use it but I don't know about the SDRAM specs. I
>> got it running in 229 Mhz on DE0-nano it it seems to work, despite the
>> datasheet said it operates in 133Mhz...
>>
>
> Is it possible that overclocking the memory is responsible for flickering
> pixels in graphics mode?
>
>  But I don't do any refresh, it writes and reads so fast that refresh is
>> not needed and would certainly impact the process.
>>
>
> That's interesting.  I guess the access is repetitive enough to do the
> trick.  Years ago I wrote assembly code for an embedded device that used an
> interrupt handler routine to step through a page of NOPs every millisecond
> or so.  There were no particular real-time constraints in play (it was a
> print buffer) and this saved some money on hardware.
>
> Steve
>
>
> --
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco
>