Re: graphic modes

On Sun, 24 Jan 1999 Jeff Gill wrote:
>Hi, I'm using a A4000 with  Picasso II under NetBSD 1.3.3.  I have been
>tweaking my graphic modes lately, trying to get the best looking display
>possible and was wondering about something.  I'm using a Viewsonic
>V775, which states that it is capable of displaying a noninterlaced 1600x1280
>at 68 hz.  It will sync vertically from 50-120hz, and horizontally at 30-
>85khz.  Can I generate a 1600x1280 NI from my Picasso II, or is this beyond
>the capability of the card?

AFAIK, The Picasso II is using a maximum dot clock of 85MHz.  To get the
maximum refresh rate for this resolution the following formula can be used:

  85,000,000Hz / 1600 / 1280 / 1.2 / 1.3 = 26.6Hz

1.2 and 1.3 are estimated correction factors for the time the video beam needs
to reset it's position vertically resp. horizontally after each scan row/frame.

Your monitor won't sync on any signal below 50Hz, so you definitely need
to set your Gfx board to interlace mode at this resolution.  You still will
not like the result, expect the display to flicker badly.

Yours,

    Michael Böhnisch