Can anyone answer this... if the scope is connected by the parallel LPT1 port , (which according to the IEE 1284 standards , has a max throughput of 4.5Mbs in ECP on a PCI bus ) how can it capture frquencies upto 50mhz , or in the case of the Pico scopes , 100mhz at 12 bit...

Rob, data transfer is not in real time. There is first a pure sampling phase of making those 4096 samples, which at the same time are stored into 'big' static RAMs, mounted on PCB. Then, afterwords, data is transfered via parallel port. Then again there's a pure sampling phase, and again...
You can notice this performance, when you have a look at actualization speed of screen display. It's so 'slowly', that tons of data can be transferred between two actualizations.
Also, in the 1GHz/sec sampling mode it takes some seconds for completing display. This is another indication that data transfer is not in real time.

Regards,
Kai