At 10:42 PM -0700 8/1/00, Monroe Williams wrote:
>on 7/31/00 9:33 AM, Henry B. Hotz at hotz@jpl.nasa.gov wrote:
> > Well I hooked up one of the really old (now anyway) Apple color
> > monitors which are fixed frequency 35 KHz horizontal by 66 Hz
> > vertical and it works just fine with OF, NetBSD, and X.  In fact it
> > looks better than the nearly-as-old Apple 19 inch because it's
> > crisper and the colors are more saturated.
>
>Are you sure the old monitor isn't just more adaptable than you think?  I've
>spent pretty much time trying different settings on one of those Mac->VGA
>adapters with DIP switches and I've never seen the monitor sense lines make
>a bit of difference in the video timing on /chaos/control.
>
> > It makes sense that Apple would support their lowest common
> > denominator scan rate in OF.  I don't have a PC monitor to try, but

I tend to believe that OF ignores the sense lines.  I was just trying 
to cover all the bases.  As for the monitors being flexible enough to 
handle a different refresh rate:  I don't know, though I doubt it 
would extend down to the VGA rates.  The specific monitor is one I 
inherited at work and I don't even know its age for sure.

I will say that the original Mac II with this monitor type came out 
before multifrequency monitors were common on PCs.  Narrow frequency 
response on the sync lines was considered a noise-rejection feature 
at that time.

>120Hz is in fact _not_ a reasonable default.  There is a timing-related bug
>in the Open Firmware driver for /chaos/control that causes it to fail to
>properly initialize the video controller.  On my G3-upgraded machine, it
>_usually_ comes up at 120Hz.  Repeated reboots will occasionally make it

I've never actually seen this symptom.  I *have* seen it come up with 
varying apparent size differences on the screen and varying apparent 
display area location on the screen.  Even with the patch installed 
OF does not properly initialize the contents of video memory.  I get 
diagonal rainbow patterns left in the margins until X starts up.

In fact I run X on the machine now just to make the screen look 
pretty.  I actually use the machine as a server.  Need to enable the 
screen saver on X though. . .


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h.b.hotz@jpl.nasa.gov, or hbhotz@oxy.edu