[Coco] Q: CoCo2 border

[Theodore Evans (Alex)]

On Jan 11, 2004, at 12:03 PM, jdaggett at gate.net wrote:

> Alex
>
> The MC6847 chip is noninterlace.The chip is doing 262 vertical
> lines. One field per frame. Therefore the frame rate is ~ 60 frames
> per second. Well above the flicker rate. Movie projectors are 24
> frames per second.
>
> Per the 6847 spec
>
> 13 vertical blanking
> 26 top border
> 192 visable
> 25 bottom border
> 6 vertical retrace.

So there are 39-45 lines of border at the top and 25-31 lines at the 
bottom.  And PAL is 25/50 Hz as is SECAM.  The flicker rate is 
dependent on a number of environmental conditions.  They tend to be 
exacerbated in interlaced video on computers (i.e. Amiga NTSC/PAL lace 
modes or interlaces 1024x768 VGA) because there is a great deal of 
contrast between adjacent lines and computer displays tend to use 
fairly fast phosphors.