On Fri, 20 Dec 1996, Marc Malagelada Duch wrote:

> 
> Somebody said that there is a interface to use the VR290 
> with a PC.
> 
> Is there any good soul that may pass the scheme to me?
> 
> Thanks.
> 
> Marc.
> 
         The VR290DA uses composite sync if it has four BNC connectors in
the back. What you will need to do is build a circuit that takes the
horizontal and vertical syncs and mix them. Since these sync signals are
TTL levels, I have used a 74LS86 exclusive OR gate to do this. 

                 1        
         H---------\\~~~~\ 3      4     
                 2  ||    |---------\\~~~~~\ 6    8    
             gnd---//____/         5 ||     |------\\~~~~~~\ 10
                  11           |----//_____/      9 ||      |-- out
         V---------\\~~~~~~\   |             gnd---//______/
                    ||      |--| 13    
             gnd---//_____ /       
                   12
                                   7---gnd   14---Vcc (+5v)


	If any component of the signal need be inverted, move the 
grounded input of the corresponding gate to Vcc. Any questions? :)

psapp@cnct.com - Is there life after Ultrix for VS3100?