Ask Max: Can You Run a PowerBook in Dual Display Mode?
Is it possible to use one PowerBook to run the display of another PowerBook's in dual display mode?
The short answer is no you can't do that, but I have never been the short answer kind of person. Laptop displays are not just thin monitors bolted to a computer but instead are integrated components of a whole computer system. There is no monitor port inside a laptop that you could connect up to from another computer. That is why I say that you cannot use a PowerBook as a second monitor. But I just can't leave your question alone.
There was once some PC software that could take any two computers and make them act as one system. I saw it once on an old TechTV program called "The Screen Savers," and after that never heard of it again. I cannot remember the name and I do not think they ever made it into a real product you could buy, but it was exactly what you wanted.
The only other option that came to mind was importing a video feed from your main PowerBook onto your "second display" PowerBook. By connecting the S-Video connection of the main PowerBook to a FireWire Video Converter you could display a TV quality version of your spanned desktop on another computer. The "Second Display" PowerBook would need to be running a viewer application like Video Viewer and be connected to the FireWire Video Converter.
Now, both these ideas are not very useful to you in any practical application. The program I saw was not produced and was made only for Windows and the money you would spend on the FireWire Video Converter could buy you a LCD display. Trust me, you will like the image of a LCD Display better than the TV image on a PowerBook. So my simple recommendation is to buy a second monitor.
I know this was confusing but hopefully fun to read.