Re: Laser 128

[spec@vax2.concordia.ca (vax2.concordia.ca)]

In article  bheinz <bheinz@hawk.phantasy.com> writes...

>I'm not sure that a CGA monitor will work with the Laser, depending on the
>refresh rate of the monitor (it needs to be 15Mhz, not the modern standard
>30, but and old CGA MAY support this.)

    You mean the horizontal scanning frequency, which is often 15.75 kHz
on composite, digital and older analog RGB displays. The refresh rate has
to do with the vertical scanning frequency (i.e. 56 Hz, 60 Hz, 75 Hz, etc).
and I think affects how quickly the gun "sweeps" down the screen to redraw
scanlines, or time between refreshes taking place. The higher the refresh,
the less flicker you'll see out of the corner of your eye as you turn your
head away from the screen (especially noticable on an all white background).
It has nothing to do with whether the video source can sync or not.

    CGA and EGA monitors were 15.75 kHz, same as those composite and RGB
screens sold for the Apple II. It's VGA and SVGA displays that started
using double (or more) the h-scanning frequency (also why you don't hear
that high-pitched squeal when they're turned on with no video source ;)

Mitchell Spector
spec@vax2.concordia.ca