Hi Bob,

PicoScope can only operate one unit at a time.  I have run a 212 and a 3000 simultaneously with one using PicoScope 5 and the other PicoScope 6 but neither are at full efficiency and are not synced, of course.

If you want a four channel scope, I would go with our PicoQuad upgrade kit.  Then you will have a true four channel with each channel synced to within 50 nanoseconds at all times.  For all practical purpose, that's simultaneous sampling.

The upgrade kit is a good value with all the goodies you need for two more channels. 

http://www.autonerdz.com/picoquad.htm#_Upgrade_to_PicoQuad