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Not only incomplete and needlessly imprecise, but inaccurate with it (21.8 doesn't round to 23; 15.7 should by rights round to 16), enough that a fixed freq monitor might not actually sync that incorrect rate. Also if we're talking Amiga (and other non-PC) support, you could take your pick of 23, 25, 27 (as supported by the bisync Rangers), 28 or 29kHz, alongside e.g. 18.4kHz... And I've never known an LCD, including some quite old VGA-port equipped TVs, that can't accept 72 and 75Hz input. |
Seems we skipped XGA even though it came between VGA and SVGA, it was a particular badge of capability for an early Multisync to reach its 1024x768 interlaced mode (as well as SVGA's 800x600 non-interlace) and its characteristic resolution and even interlaced scan mode continues to be well supported. Also, what's with all the special-wiki-code unspaced em-dashes? I think I've caught them all now. |
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Multiscan monitors appeared during the late 1980s,<ref>{{cite web|title=MultiSync 25th Anniversary{{Snd}} The Evolution of the MultiSync|url=http://www.nec-display.com/ap/en_display/25th/}}</ref> offering flexibility as computers moved from earlier standards such as [[PAL]], [[NTSC]] and [[Color Graphics Adapter|CGA]] to higher scan-rate standards such as [[Enhanced Graphics Adapter|EGA]], [[VGA]] and [[SVGA]]. Normally, a different fixed-frequency monitor was required for each of these standards. <!-- the wiki articles on VGA etc. should already cite all needed information -->
# [[PAL]], [[NTSC]], [[Color Graphics Adapter|CGA]]: ~15.7 kHz horizontal scan,
# [[Enhanced Graphics Adapter|EGA]]:
# [[VGA]]:
# [[
# [[SVGA]]: 31.5 kHz ~ 100 kHz+ horizontal scan, 48 ~ 160 Hz+ vertical scan, most commonly 56 ~ 85 Hz at 35 kHz and up.
With the introduction of SVGA, multiscan monitors became standard for personal computers supporting a range of resolutions and refresh rates. A typical screen resolution of the late 1990s was 1024x768 at 85 Hz<!-- need to find archived personal computer manufacturer product listings and web browser statistics for citation -->, requiring a horizontal scan rate over 68 kHz,<ref>{{cite web|title=Modeline Calculator|url=http://www.arachnoid.com/modelines/}}</ref> yet during system boot the [[Power-on self-test|POST]] display and [[operating system]] splash screen would be displayed at the standard VGA 31 kHz. Many [[MS-DOS]] and [[Windows]] computer games of the time would also switch to a lower resolution for greater compatibility, more colours, improved performance or to reduce the [[video memory]] required by the [[frame buffer]].
Depending on the design of the monitor, there may be several discrete frequencies supported. For example, a monitor designed for use with CGA, EGA and VGA standards could elect to support 15.7 kHz, 21.8 kHz and 31.5 kHz horizontal scan rates. Alternatively, the monitor may be designed to support a continuous range from 15 kHz to 31 kHz or more (with the original NEC Multisync, giving its name to the type, supporting 15 to 35 kHz and, at least unofficially, being just-about capable of SVGA and XGA). <!-- links to product manuals for old multisyncs would be useful here, or usenet -->
A multiscan monitor does not need to support all possible video formats. Most modern multiscan computer monitors support a nearly-continuous range of horizontal scan frequencies from 31 kHz up to 100 kHz+, omitting support for the older 15 kHz
Fixed-frequency [[Cathode ray tube|CRT]] monitors, and multiscan CRT monitors that only support a set of frequencies, may upon receiving scan frequencies outside design limits cause damage to the monitor. This is especially true for horizontal scanrate, which in CRT monitors is associated with higher voltages and power levels. A resonant circuit is commonly employed, restricting the allowable horizontal scan rates to one or more very narrow ranges. Not all fixed-frequency monitors are vulnerable to damage, but it is never safe to assume this. Most modern multiscan monitors are [[microprocessor]] controlled and will refuse to attempt to synchronise to an unsupported scan rate, which usually protects them from damage.
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