6 Jun
2010
6 Jun
'10
7:16 p.m.
I blew one of the biggest deals of my life a while back. A barely used *color* NCR PC4i.
And free to boot. It had a horrible death.
Well I do have a few green screened PC4s. Would like to swap out the monitor section.
Came across a Samsung EGA monitor. The PC4i had 400 lines of resolution, the EGA 350.
I've been told in some circles it was common to display that sort of video on
something *close*. Are there inherent dangers (x-rays, etc.)? Do you abnormally shorten
the lifespan of the monitor by doing that?
7 Jun
7 Jun
10:24 a.m.
--- On Sun, 6/6/10, Chris M <chrism3667 at yahoo.com> wrote:
Well I do have a few green screened PC4s. Would like
to
swap out the monitor section. Came across a Samsung EGA
monitor. The PC4i had 400 lines of resolution, the EGA 350.
I've been told in some circles it was common to display that
sort of video on something *close*. Are there inherent
dangers (x-rays, etc.)? Do you abnormally shorten the
lifespan of the monitor by doing that?
The number of lines of resolution isn't as important as the sync rates. EGA and CGA
use different sync rates, and thus are not compatible. Similarly, PC style monochrome also
runs at a different frequency. You need to figure out what "mode" the machine
uses, so you can pick a replacement monitor accordingly. Also, wouldn't the monochrome
version of the machine have different video electronics? I know nothing about this
computer, but you'd probably need to find the color graphic board in order to drive a
color monitor. But... I don't know. The Compaq portable used a built-in monochrome
monitor at CGA sync rates, but could drive an external color monitor.
Another thing you have to worry about is the type of video signal. Is it analog, or is it
digital? PC monochrome, CGA and EGA are all digital. VGA is analog. Many other home
computers used analog video (Amiga, Atari) at NTSC sync rates (15.75khz, same as CGA), and
while they can be connected to a CGA monitor, the color pallette will be severly limited.
You can modify a CGA monitor to make it analog, however.
Connecting the incorrect monitor shouldn't immediately destroy it. At least, I
don't think so. I'm sure it is definitely *possible* to damage a monitor like this
though - I've just never seen it done. Be prepared to shut it off if you hear any
weird whining. For example, a CGA monitor wired into something that produces EGA sync
rates produces a picture that won't sync up - and if you fiddle with it enough you can
actually get multiple images overlapping.
-Ian
4:35 p.m.
On Mon, 7 Jun 2010, Mr Ian Primus wrote:
The number of lines of resolution isn't as
important as the sync rates.
EGA and CGA use different sync rates, and thus are not compatible.
Similarly, PC style monochrome also runs at a different frequency. You
need to figure out what "mode" the machine uses, so you can pick a
replacement monitor accordingly. Also, wouldn't the monochrome version
of the machine have different video electronics? I know nothing about
this computer, but you'd probably need to find the color graphic board
in order to drive a color monitor. But... I don't know. The Compaq
portable used a built-in monochrome monitor at CGA sync rates, but could
drive an external color monitor.
Actually, the Compaq "portable" (the luggable, not any NEWFANGLED) could
do both CGA AND EGA rates! Compaq made an EGA card for it (a little
rare) that included the midboard connector for the internal monitor!.
Another company (ATI?) made an add-on board (more than a little rare) for
one of their EGAs for use in Compaq luggables.
Connecting the incorrect monitor shouldn't
immediately destroy it. At
least, I don't think so. I'm sure it is definitely *possible* to damage
a monitor like this though - I've just never seen it done. Be prepared
IBM monochrome monitor to CGA "But the connector fits!"
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chrism3667＠yahoo.com -
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ian_primus＠yahoo.com