iMac VGA out???
The 15" iMac has its VGA output tied to the resolution of the LCD ( I think ).
This follows fairly straight forwardly from the fact that the GF2mx has an internal TMDS and CRTC. Im guessing that Apple just used both outputs because it was convenient.
However, the GF4 mx has two sets of TMDS' and CRTC's, and the tech specs states that the video out is still bound to the limits of the 15" model.
What are the odds that on the 17" the vga output is actually a real second video out ( no extra cost, its built into the chip ), and it will only require a driver modification to enable it properly????
This follows fairly straight forwardly from the fact that the GF2mx has an internal TMDS and CRTC. Im guessing that Apple just used both outputs because it was convenient.
However, the GF4 mx has two sets of TMDS' and CRTC's, and the tech specs states that the video out is still bound to the limits of the 15" model.
What are the odds that on the 17" the vga output is actually a real second video out ( no extra cost, its built into the chip ), and it will only require a driver modification to enable it properly????
Comments
Apple disables spanning in software. This is a dirty trick.
Bad Apple!
I believe ( from everything that Ive read ) that the gf mx has one on board display generator - it has outputs for TMDS, analogue, and video. To get a second display and external ramdac needs to be added. Apparently you can get dual tmds ( DVI ), but it isnt clear if this is on chip, I think a second external tmds transmitter needs to be added.
This leads me to believe that Apple is taking advantage of the fact that two identical outputs are generated by the gf mx, the digital goes to the lcd screen, and the analogue goes to the external port. Its a bit of cheapness ( not putting the external ramdac in for the second port ), but fair enough.
The gf4 mx used in the 17" iMac has dual display paths built in, full TMDS, analogue, and video. This means that Apple dont need to add any extra hardware, and they could have real dual output. It seems even more possible, because the vga out generates the standard 15" resolutions ( according to the tech specs ). This would require setting up the second display generator to handle those, while the internal screen runs at its resolutions.