The USB to parallel port adaptor can download 1000 Hz in streaming mode continuously.
The unit does not have any memory on board and thus does not collect a block of data and then download it, the only units that do this is the ADC2xx range. Therefore it downloads the readings one at a time again with streaming and buffers it in the driver functions.
We have had some issues brought to our attention recently by other customers using the ADC-100 and USB to parallel port adaptor, which are listed in the Buglist. These are due to be resolved in the coming months, but if you do have any problems with it please bring this to our attention.