On 19 Oct 99, at 12:48, David George wrote:

> I have a problem changing the resolution on my monitor from
> 640X480 to 1024X768. The monitor supports the latter as its
> maximum resolution. if I select it either on the fly or change it
> and reboot I get flickering horizontal bands of colour and have to
> reset it to 640X480.
>
> I have the following:
>
> SBM 14" svga monitor (not DPMS or PnP)
> Tseng ET-6000 PCI VGA 2.3 meg colour card.
> The OS is WIN95 B (OEM)
>
> I do not have enough technical experience to know for certain but
> I suspect that the graphics card does not have enough ram to
> enable it to switch to the higher resolution. Is this correct? If
> not, how much ram does it take to support this mode?
>
> I have recently updated the driver for the card but it has not
> made any difference.
>
> Please help me out of my ignorance!

  There are two ways common ways that a video image may be displayed:
 non-interlaced (row by row) and interlaced (where the image is drawn
in alternating passes, one drawing the odd rows and the other the
even rows.  An interlaced display runs at a lower frequency, but
typically produces a less crisp image, with a slight "flicker" to it
that bothers some people.
  I believe that your monitor may be capable of 1024x768 only in
interlaced modes; the horizontal bands of colour are appearing
because the video card is providing a higher frequency (trying to
display non-interlaced) than the monitor can handle.
  There should be a way -- probably through the Display Properties
applet, for you to adjust the video frequency and thus force the
video card to generate an interlaced output signal.

  Besides the flicker, I should point out that most viewers consider
1024x768 a bit cramped on a 15" monitor, and would never recommend it
for a 14".  And operating your monitor beynd its rated frequency can
land it in the repair shop sooner than you'd like....

  As to how much RAM is needed, that will depend on colour depth.
However, 2.3MB *should* be able to support 1024x768 resolution at 24-
bit colour depth.  If your card did not have enough RAM, the Control
Panel applet would never let you test that setting at all.

David G

         The PCBUILD web site always needs good submissions.  If
          you would like to contribute to the website, send any
               hardware tech tips or hardware reviews to:
                           [log in to unmask]