Re: NTSC Monitor Vs Apple IIgs' Monitor

[pausch@saaf.se (Paul Schlyter)]

In article <pan.2005.10.20.18.47.32.155452@emeraldcity.gov>,
The Wizard of Oz  <wizard@emeraldcity.gov> wrote:

> On Thu, 20 Oct 2005 07:13:39 +0000, Paul Schlyter wrote:
> 
>> In article <pan.2005.10.19.20.58.14.862648@emeraldcity.gov>,
>> The Wizard of Oz  <wizard@emeraldcity.gov> wrote:
>> 
>>> Of course I have a monochrome NTSC monitor
>> 
>> No you don't .... a "monochrome NTSC monitor" is an oxymoron.
>> 
>> NTSC is a system for *color* television.  A monochrome monitor does not
>> show any color and therefore lacks the circuitry needed to decode NTSC
>> signals.
> 
> If I'm wrong then correct me. I thought the video out jack on a //e sent
> out an NTSC signal. At least that's what we've been calling it here for
> years.

It does - and if you had said that youe //e outputs NTSC video I would not
have objected, since that is correct.

> I have both colour and monochrome monitors which will accept signals from
> both a //e (and my Linux box) as well as a VCR directly. I haven't heard
> of anybody connecting one of these North American monitors to a PAL VCR,
> but that doesn't mean it can't be done.

Your colour monitor would not work with a PAL video signal, but your monochrome
monitor is likely to also work with a CCIR (62-line 50 frames/sec) video
signal.  Of course the monochrome monitor ignores any colour signal, to that
monitor only the b&w part of the signal is relevant.

> As far as the decoding part of it is concerned. Taking an NTSC compatible
> signal and throwing out the colour data as part of the design is a form of
> decryption. Think back to your numerical analysis class (they didn't teach
> that here until third year). Think of the signal put out by the computer
> as a noisy channel. The monitor extracts information it can use from the
> data stream. The rest is ignored. Presuming the originating signal ls an
> NTSC signal, this would make any monitor accepting it in whole or in part
> an NTSC compatible monitor. Which we've been referring to as an NTSC
> monitor.
> 
>                                 Later
>                                 Mike

I've been told in another post that NTSC not only refers to the color signal
standard but also to the underlying b&w signal standard.  The corresponding
b&w signal standard for 625-line 50 frames/sec television, which is
used in e.g. Europe, is called CCIR.

Since your monochrome monitor probably can accept b&w signals both according
to the NTSC and CCIR standards (it's mostly a matter of adjusting the vertical
sync when you switch from one to the other - the horizontal sync frequencies
are so close to one another in the two cases that the monitor easily can
sync to iether of them) I still think it's superfouous to call your monitor
an "NTSC monocrhome monitor" since it might as well be a "CCIR monochrome
monitor".

-- 
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