Screen replication

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A group of 5 people sitting at a table, with one doing a demo on a
laptop.  Hard for everyone to see.  People need to crowd around.
Others have laptops.  Could you replicate the screen live to those
laptops?  Or at least to one laptop?

That's my question.  Below, some thoughts:

- If you had a real monitor, it could plug into the first laptop's
video-out.  But monitors are too big to carry around.

- Unfortunately, laptops don't have video-in.  Could you use USB-in
and use it to write to the 2nd laptop's screen?

- Consider using the 1st laptop's USB-out.

- Write a driver to handle the USB data?

- Is there software already available?

- Send via Bluetooth?  Probably too slow.

- Send via Internet?  A shame, and connection may not be available.

- Send via WiFi, without using any external network?  Can such a thing
be done?  Why not?  Each laptop has an antenna, and is capable with
sending and receiving wirelessly.

- I found this product, which shows that it is possible to solve one
part of this:

WiJET.Video - Wireless Presentation Solution
for Projectors, LCD, Plasma and CRT Displays

Thanks for any suggestions...

Re: Screen replication wrote:
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Look for "screen sharing" and "web conferencing" tools.
Using the network for sharing, is about as convenient as
it gets.

Even mid sized firms, may have their own Audiovisual tools, such
as a projector with VGA input and a pull down glass bead
screen for projection. If a firm has a meeting room, it
might have the basics in terms of amenities. Or, you can
carry your own projector around with you. With the right function
key sequence, the laptop screen output can be sent
to the VGA output instead. The nice thing about a projection
system, is it preserves the dynamics of your presentation.
Many other schemes will update pieces of the screen, in a
distracting way. Using a projector means you see the real
computer output, without interpretation, compression, or


Re: Screen replication

Paul wrote:
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I'll just add to what Paul says by saying this is trivial to do with one
of the many VNC variants out there, a router (or even a switch), and
some cable.

Re: Screen replication

My situation is that a few of my friends meet weekly to keep up to
date on programming technology.  We just meet in a coffee shop or food
court.  No one minds if we just sit there quietly.  Except that
usually one of us has to stand up to see the screen of the person

So this is a small-time operation... we couldn't use a projector.
Also, there's no Internet connection.

While it sounds inefficient, it really almost works well.  The group
is small enough.  I just thought I could improve it slightly if one of
the spare laptops could be used as a "mirror".  We have all this
powerful hardware (laptops) around, and it is the 21st century.  This
should be possible!  :-)

The bandwidth would be low, as we usually just look at text in Visual
Studio.  The most screen activity would be after a Page Down or window-
switch, but the screen would usually then have time to update.  Of
course a projector would "preserve the dynamics" better, but I think
it would be acceptable.

Thanks Paul.  I looked at your link, and I see many variants on XP's
Remote Desktop.  I read Wikipedia on VNC (thanks for alerting me to
the term, Grinder), and I understand it is the base protocol used by
these products.  The remaining question is the network part.  While
I'm generally knowledgeable about computing, I know nothing about
setting up networks.

- Could I plug one computer into another with some kind of "null
cable"?  I know they existed for serial cables.  Do they make them for
Ethernet cables?

- Or is it just better to use a switch.  I think they're cheap enough,
and they'd have the advantage of allowing multiple connections.  OTOH,
a cable is less bulky.

- If you make this direct network connection, does a typical Windows
computer detect it and set up what it needs?  Or do you have to set up
fake IP addresses or something?  Would you be using TCP/IP at all?
There's no Internet involved here.

(Does anyone mind that I didn't quote all the text?  We all have
access to the previous messages, right?)

Re: Screen replication

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  Your small group of laptop owners might consider this:


Re: Screen replication wrote:
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LCD monitors aren't much heavier or bulkier than a laptop computer and
would involve less potential for software configuration issues. I've
seen some that come in corrugated cartons that are the size of a SMALL
suitcase and even include a carry handle.

The Ethernet equivalent to a null modem cable is called a crossover
cable. At first glance it looks like a regular Ethernet cable, but two
of the wires are crossed compared to the regular cables. With a
crossover cable you can network EXACTLY two computers (tower or
notebook/laptop form factor is irrelevant) without a switch. For more
than two computers you would need regular Ethernet cables and a switch.
Many wireless routers include a switch with four wired Ethernet ports.

I have also seen devices that allow two computers to be connected
through their USB ports.

With the Generic OEM Windows XP installation CD I have booting a
computer with the Windows XP CD produced a menu that included a network
setup wizard. The Wizard detected the Ethernet connection and made most
of the necessary settings. The one setting that the wizard prompted the
user to enter was the Windows work group name. The SAME case sensitive
name had to be entered on each computer. The wizard on the CD was even
compatible with a Windows 98 computer. I'm not certain how to access the
wizard without booting with the CD, but I believe it is duplicated in
the hard disk installation.

Setup instructions are probably included in router user manuals as well.
The last router I purchased included a PDF manual on a CD and lacked a
printed manual.

Re: Screen replication wrote:
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I don't know where you are located but you might be able to locate a better
meeting site using
one from this link. /

If all else fails you may be able to work out something by bringing along a
wireless router and using
just the wireless side of it to connect your computers together. True you
will need to locate a
working power outlet but it does give you another option.

If you lived in my area I would suggest relocating your meetings to one of
the coffee shops or food
courts that provide free internet access. Just about all of them in my area
now offer free internet access,
a few require password access but it's still free. Our local library offers
that as well as places to have
meetings provided we schedule them in advance by a week of so. My library
even offers it's
own coffee shop that includes free internet access.

Same goes for just about any Borders, Waldens, or Barnes & Noble book
stores. Once you have a
place with internet access there are many free programs available to do what
you want.

Check out the information a the following link to my local computer club .
Scroll down to the "March 11th, 2009, Wednesday - 7PM" article. You may be
able to use one of the
listed programs to do what you want. Microsoft SharedView would work just
fine for a group the size
you indicated. No need for Skype in your situation if everyone can hear the
other with out it.

Re: Screen replication wrote:
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... snip ...
Quoted text here. Click to load it

Some useful links on quoting:

You didn't quote ANYTHING.  See the links above.  It takes
virtually zero effort to snip the areas you are not responding to.
The secret of proper quoting is proper snipping.

And no, you have no guarantee that readers have access to previous

 [mail]: Chuck F (cbfalconer at maineline dot net)
 [page]: <
            Try the download section.

Re: Screen replication wrote:
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When you connect a computer to your home router, and in turn to broadband
Internet, you'd normally use DHCP. That automatically deals out IP addresses
from a block you define, on an as needed basis. For example, it might be
a block from to The router may have a setting
to define the start address and length of the block (four addresses in
my example).

When a computer connects to a DHCP device, the DHCP server gives out an
address to use. And the address lasts for the period of the lease.

When connecting two conputers together directly, neither would likely be a
DHCP server. You can define static addresses for each computer manually,
using the network setup stuff in Windows. You could make one machine and the other machine

The is a block of private addresses. They aren't intended
to be routed over the Internet. So, you would not expect a person in
another country, to have a public IP address in that range.

There are some other private address ranges. I think there is something
beginning with And there is the APIPA address, the one
Windows uses, if it cannot contact a DHCP server, and is left to figure
out the address on its own. I haven't played with this.

Automatic Private Internet Protocol Addressing (APIPA)

In terms of cabling, there are a couple cases to consider. The computer
could have a 10/100BT NIC. That operates at 10 Mbit/sec or 100Mbit/sec.
Of the eight pins on the Ethernet connector, only four are essential to
wire up (1,2,3,6). You'd want a "crossover" cable in that case, because there
is no guarantee the NIC has MDIX capability. If the NIC support 10/100/1000BT
(gigabit Ethernet), the interface uses all eight pins, and the interface
will also have MDIX. You can use a straight cable for that, and an MDIX
capable NIC will put the "twist" in itself. My current computer has
a "mouldy oldy" Ethernet chip, so I'd have to go through my junk box, to find
the only crossover cable I've got. Some of my older computers have MDIX,
so hooking them up was less of a hassle. Of a pair of computers, all you'd
need is one MDIX capable computer, to be able to use a straight thru cable.

So changing from DHCP to static addressing, will get you running
pretty quickly. Pack a crossover cable, in case both machines
are 10/100BT. MDIX can even figure things out, if you use a crossover
cable. (My crossover cable, has one red plastic hood and one blue hood.
That is how I can tell it from the other cables, which have matching
colors on either end.)


Re: Screen replication

If you have a s-video output and a usb capture card you could do it.
IE plug the out put from s-video into the usb capture card.

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