From: Mike Wiese <mikew@apple.com>
Subject: Re: Hook a 16" SVA to Powerbook, Duodock or Quadra??
X-Useragent: Nuntius v1.1.1d12
Date: Mon, 9 Nov 1992 04:32:07 GMT
X-Xxdate: Sun, 8 Nov 92 04:33:53 GMT
X-Xxmessage-Id: <A7232A31C2010C85@wiese.apple.com>
Organization: Apple Computer, Inc.

In article <D2150035.i3nf12@outpost.SF-Bay.org> Michael Peirce,
peirce@outpost.SF-Bay.org writes:
>In article <1992Nov6.205714.8682@ac.dal.ca> (comp.sys.mac.hardware), 
>arun@ac.dal.ca writes:
>> Is it possible to hook up a SVGA 16 inch monitor ie Sony 16 inch or
any other
>                                                      ^^^^^^^^^^^^
>> brand to the Quadra or the new DuoDock or the Powerbook 160/180 and
get the
>> 832X624 output as you would get from a Apple 16inch Display. Has
anyone had
>> any experience with this..
>
>I have a Sony CPD-1604S 16" monitor hooked up to my Q900.  I *think*
>this is a SVGA monitor, though frankly I don't really know since its
>not important to me so I never asked.  All that matters is that it works
>great with my Q900.

If you don't know, don't post. Let's keep the information quality high.

Most monitors are designed to work at one (or a few) vertical and
horizontal
scan frequencies. The vertical frequency is how often the whole screen
is redrawn by the electron gun, the horizontal is the rate lines of
the picture are scanned.

For example, the Apple 16" RGB monitor is 832 pixels x 624 lines, with
75 Hz vertical refresh. Multiply 75 by 624 and you get about 48600, so
the horizontal is at least 48.6 KHz, not counting the blanking. The actual
horizontal frequency is 49.7 KHz.

SVGA monitors do 800 x 600, at 56 Hz (can you say flicker?).
600 times 56 is 33600, including blanking the actual rate is 35.16 KHz.

As you can see 49.7 KHz is a lot higher that 35.16 KHz, so any random
SVGA monitor is not going to work. One reason SVGA is cheaper is the
lower frequency parts are less expensive. Same goes for VGA vs the
Apple 13"/14" - the Apple monitor has a higher refresh rate.

To help us out of this mess of zillions of different video modes,
monitors that can deal with a range of horizontal and vertical scan
rates were invented, like the Sony multican and NEC multisync. They
do their best to display whatever video signal you feed into them,
within limits.

==> The Sony 1304 HG (13") can handle up to 50 KHz horizontal, so it can
display Apple 640 x 480, and Apple 16" 832 x 624 video. The Sony 1604S
(16")
can also display both modes.

The LOWER limit on the Sony's is around 30 KHz, so you can't run the 15.7
KHz
signal from your VCR into them (even if you converted it to RGB). But
they do
support the various VGA and SVGA modes.

Apple has also seen the light and realized some people would be willing
to accept lower quality video to save $$$. So starting with the LC, Macs
with built in video support VGA. The Quadras, PowerBook 160, and 180
also support SVGA. Note that since IBM didn't establish SVGA as a
standard, there is more than one type of SVGA, so your mileage may vary.

One cool thing about Macs is they automatically adjust to the type of
monitor that is connected. For info about this, there's a new Tech note
titled "Sense Lines" that explains all about it. If you need to build
an adapter to use a non Apple monitor, check it out.

mike wiese