[Coco] No pixel wasted

[Luis Antoniosi (CoCoDemus)]

I reduced the speed from 229Mhz to 114Mhz, the SDRAM works better now:

http://imgur.com/MY0ExuW

It also fixed the artifact in coco1/2 graphics screen.

But for coco3 games like roboco, thexder I still get some minor flickering
in some areas. Like it generates those video modes with a slightly
different pixel clock ? I have a 1986 GIME only.

All the other resolutions are pixel perfect: 32, 40, 80 columns, pmode 1,
2, 3 and 4.



Luis Felipe Antoniosi