Differences among DE2 Boards fo Video in

[Altera_Forum]

Hi everyone 

 I'm try to run the video-in demo included in the University program (as is).  I've a couple of DE2 boards (one a bit older than the other) ... but no particular differences should be among them, instead testing the demo on both of them:  In the oldest one something related to the imput image appears on the VGA but the image is not stable and after few seconds it desappear.  With the newest one, an image of the internal SRAM appears very stable on the VGA, but no information  from the TV decoder apper.  Why two quite identical boards performs in a so different way ?  Thank you    Please note that all the demo concerning pixel buffer and char buffer works perfectly on both the boards.

[Altera_Forum]

I'm going to answer by myself  

 One slight but fundamental difference between the two boards is in the connection ao the 27MHz Clock:  In the older release there is a 27MHz local oscillator that sink both the Video decoder and the FPGA. Moreover the 27MHz LLC signal from the VideoDecoder is also used as input by the FPGA. In the newest release the local oscillator is a 28MHz oscillator used only by the decoder. The decoder however generate a LLC clock signal at 27 MHZ that sink the FPGA on the same two pins used in the previous version

[Altera_Forum]

Another self-answer: 

 A significant differnce between the two boards is that the oldest one mount a video decoder ADV7181B while the new one adopt a ADV7180 (which must be configured with different I2C data).  However since the ADV7180 is the same mounted on DE2-70, we can program it using the University program block but setting the configuration block for the DE2-70 (even if we are using the DE2-35)