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From: jcp@brl-tgr.ARPA (Joe Pistritto <jcp>)
Newsgroups: net.video
Subject: Re: monitor query: composite color input vs. RGB
Message-ID: <4269@brl-tgr.ARPA>
Date: Tue, 28-Aug-84 00:40:19 EDT
Article-I.D.: brl-tgr.4269
Posted: Tue Aug 28 00:40:19 1984
Date-Received: Thu, 30-Aug-84 11:15:31 EDT
References: <918@bbncca.ARPA>
Organization: Ballistics Research Lab
Lines: 47

There are several systems for sending color signals to a monitor, in order
of resolution (low to high)

	NTSC (American Television Standard) - uses 525 lines, 30Hz, each
		frame is actually two frames, (interlaced).  This is
		ALWAYS sent over a composite (single) cable.  This can
		be made from the PC's composite video via an RF modulator,
		(about $20 from any video store), but you will lose every
		thing over the PC's medium resolution mode on the color
		board.  (and the result isn't EXACTLY NTSC so it doesn't
		work on all TV's, Sony's work excellently though).
		Top bandwith is 3.5Mhz here (due to the TV sound trap)

	Composite Video - Any # lines, (usually from 400 to 600, 512 is
		popular).   Usually, this is used for 512x512 applications.
		Requires one cable.  This is often interchangable with
		NTSC above at low resolutions (320x240 or so).  The PC's
		composite video works at all resoulutions, but the high
		resolution stuff cannot be successfully converted to
		NTSC.  I believe the PC produces ~12 Mhz on the RCA phono
		plug on the color board.

	RS-170 3 or 4 wire - medium resolution graphics display standard.
		Uses seperate R, G, and B, and often sync.  Sync can also
		be added to the Green line, (but more and more it appears
		seperately).  The standard bit rate for RS-170 is 12-20Mhz
		or some such.  This is what the PC color adapter puts out
		on the multipin connector.  If you are using high-resolution
		mode, USE a RS-170 monitor!!!!!.  The color saturation is
		usually much better, (the colors aren't demultiplexed in
		the tube unit), and the phosphors are much more precise.
		The Princeton Graphics monitor is supposed to be excellent.

	RS-343 (3 or 4 wire) - This is FAST stuff, intended for real serious
		graphics work (1024x1280 at 30Hz, 512x640 at 60Hz).  The
		bit rates here are typically over 25Mhz, up to about 36Mhz
		depending on screen configuration.  Usually this is 4 wire,
		although some systems encode sync on green again.  Monitors
		for this are made by Hitachi, Mitsubishi, and most of the
		high-end graphics manufacturers, minimum price is $2K or
		so.  There ARE boards for the PC which produce this, but
		they are rare.

	I hope this helps answer your question, if not, send me mail
at JCP@BRL

						-JCP-