|
Written by Tom Mordasky
|
|
Sunday, 11 March 2007 |
|
The holy grail... sort of
 Time and time again, modding forum newbies always want to know if they can turn the LCD from their old laptop into an external display. Time and time again, the veterans patiently explain the challenges, the cost, and difficulties involved. Yes, people have tried. Nobody has succeeded. Thus, the goal has become a holy grail. Now, it looks like somebody has found it... sort of.
Screen Recycler turns any computer, Mac or PC, into an external display. It accomplishes this via a bit of nerd trickery: VNC or Virtual Network Computing. The same techniques used to remotely access and control a computer is how Screen Recycler creates its virtual screens. It involves two components, the primary application runs on the host machine and creates the virtual display. Then any VNC program running full screen on the client machine allows you to view the "new" display.
Set up
is quite easy, simply run the installer on the primary (host) machine. The
install will require a reboot. Then launch the Screen Recycler program and it
will list the IP address you will need to use in the VNC program on the screen
to be controlled. The program uses network port 5900 by default and no other
program may be running on the same port. You'll find that if anything is using this, it's often Apple
Remote Desktop or other VNC software. Once the main program is up and running,
simply launch your VNC client on the computer you wish to control and log onto
the provided IP address. The "new" display will show up in the monitor control
panel just like any other external monitor. It may take some adjusting to get
the screens arranged correctly. In addition the System Preferences do not
always correctly recognize the native resolution of the new display and this
setting may need adjustment as well.
 What about performance? There are two main factors involved in the overall
quality you will experience. The first and most obvious is the speed of your
LAN; the faster your connection the better. When I tested the
software I was using my PowerBook G4 as the host and an iBook G3 as the second
display. For my first attempt, I simply used the existing Airport connection. As
the iBook is only 802.11b the overall speed of the network was not nearly
enough to produce a usable result. The display on the iBook was a garble of
colors and the G4's display actually had problems as well, with the resolution
resetting to 1024x768. A second
attempt with a fire wire 400 cable provided a much more satisfying result.
Anything Ethernet 100 or faster should be fine.
The
second main factor in the performance of the virtual display is the speed of
the VNC client. The software is intended for connections across the web where
the refresh lag is considered par for the course. Screen Recycler comes with
its own client called JollysFastVNC. It's a limited use client designed
specifically to work with the virtual display. I found the best results by far
using this client. I tested VNC Dimension, Chicken of the VNC and VNC Viewer
and none produced nearly as quick a refresh as the included client.
Even
under the best of conditions there is a noticeable refresh lag on the virtual
display. Moving windows and objects will have a slight blur to them, similar to
the passive matrix LCDs of yesteryear (remember those?). Turning on a full motion screensaver
will give you a good idea of just how much lag you can expect. All things
considered, the lag is not too bad. Full motion video in quicktime did drop
frames but was still quite watchable. Pickier people may want to reserve the
virtual display for email or other non-intensive tasks.
The
single largest caveat to using Screen Recycler is the fact that the video
hardware on the primary machine must be capable of monitor spanning. If your
machine can only mirror a display then it will only be capable of mirroring its
virtual display as well. Macs that can take advantage of software fixes such as
Screen Spanning Doctor should be good to go once the hack has been installed.
It is an unfortunate fact of the hardware that eliminates what would perhaps be
one of the more desirable uses for this software.
Overall
Screen Recycler represents what I love best about innovation, It takes an
existing idea and repurposes it in a revolutionary new way. Kudos to the author
for writing this amazing little app!
 |
The Good: Turns any computer into an external display
The Bad: Noticeable refresh lag even under the best conditions, GPU must support spanning for it to work.
The Skinny: This ingenious little program defiantly deserves a look. Hopefully, future improvements in both the program and network technology will reduce the lag
|
|
