Not sure if this helps you:
These Apple computers supply multichannel audio (up to 8 channels) and video signals over Mini DisplayPort:
- MacBook Pro (Retina, 13-inch, Late 2012 and later) 1
- MacBook Pro (Retina, 15-inch, Early 2013)
- MacBook Pro (Retina, Mid 2012)1
- Mac mini (Mid 2010 and later)1
- Mac Pro (Mid 2010)
- MacBook (Mid 2010 and later)
- MacBook Pro (Mid 2010 and later)
- MacBook Air (Late 2010 and later)
- iMac (Late 2009 and later)
DsiplayPort and its variant Mini DisplayPort are interesting protocols because they use a packet interface to send mostly the changed data. There is no gratuitous repainting the screen with the same data (every 1/60 second or similar) as performed by almost every protocol that came before it.
This would free a lot of time on the interface for the information to support an additional display in the newly freed "dead time" when nothing has changed on the primary display. What would be needed at the computer end is a different address for the second and subsequent display(s). What would be needed at the Display-end is a display with a "daisy chain" output port (it cannot be the same as an input port because the signal drivers are set up to accept input, not drive output) to be able to pass the signal along to another display.
To the best of my knowledge, Apple has not yet taken advantage of this ability to address a second display, and at this writing these interfaces on Apple computers support only one Mini DisplayPort display.
There may be the ability to daisy-chain a second Thunderbolt display off the first Thunderbolt display in a chain, when working with a Mac's Thunderbolt connector.
But at this writing, any Mini DisplayPort device connected to that port is always the last device on the chain.
Considering I asked the original question in order to ascertain if I could use the Dell U2413 display's daisy-chaining capability (these monitors have the mentioned MST protocol through a DisplayPort output port) combined with the mid. 2010 MacBook Pro, does your statement "To the best of my knowledge, Apple has not yet taken advantage of this ability to address a second display, and at this writing these interfaces on Apple computers support only one Mini DisplayPort display." still hold through?
To simplify: I want to connect 2 external displays to my MacBook Pro hat does NOT have thunderbolt. Is my only feasible solution to use. Matrox Dualhead2Go or can I rely on the Dell's MST to do the trick, bearing in mode that I need full monitor performance, not just Mirror Mode performance?
As I understand it, there would need to be fundamental changes in the MacBook. If these were present, I am certain Apple would be hitting us over the head with how many external displays are supported, however torturous the setup and how many footnotes there were.
You should also look at this device to run an additional display. The prevailing criticism is that these kinds of devices are a bit laggy, but only you can judge how laggy is too laggy: