Re: Difference between GS RGB monitor & SVGA monitor

[dempson@actrix.gen.nz (David Empson)]

Allen Bong <sfbong@tm.net.my> wrote:

> What are the differences between a GS rgb monitor and a PC SVGA monitor?

The IIgs RGB monitor uses TV-compatible scan frequency: about 15.75 kHz.

VGA and higher resolution monitors operate at a higher scan frequency:
at least 30 kHz.

The IIgs can only output video at 15.75 kHz, and modern RGB monitors
cannot synchronize to such a slow signal, so they won't display the
image correctly.

> I ask this because I want to mail order a used IIgs without monitor from
> ebay and modify a SVGA monitor to work with it.  Could it be done?

In theory, you could get a scan doubling device which would take the
IIgs video signal as input and produce a double speed video signal as
output.  This would work with many current monitors.

For some monitors, it is possible to modify their internals to work with
the lower frequency, but I don't know the details.