First post, by vladstamate
- Rank
- Oldbie
Hi all, I have another CGA / 6845 timing conundrum.
The CGA is set up in 40x25 mode. And the registers are as follows:
Horizontal total 56 (characters)
Vertical total 31 (characters)
Vertical adjust 6 (lines)
Characters are 8x8. So that gives me: 56 x 8 x ( 31 x 8 + 6 ) = 113792 (pixels). This is how much the beam in the CRT is expected to cover in a frame in terms of time. But I am also running at 60fps. So in a second, the CRT timing is covering 113792 x 60 = 6,827,520 "pixels". Now those are not actual pixels of course because some of them exist to cover for vertical and horizontal retrace timing.
But regardless from the point of view of the 6845 in a given second it generates pulses for 6,827,520 "pixels".
Does that make sense at all?
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