All of the code from the SampleCell INIT was rolled into the DigiSystem INIT as of version 3.0.3. If you are running an earlier version of the DSI, then you also need the 2.04 version of the SampleCell INIT. So the required extension(s) for SampleCell 2.1 would be:PCI Macs:DSI 3.0.3 (or later).NuBus Macs:DSI 3.0.1 (or earlier) with SampleCell INIT 2.04, or DSI 3.0.3 (or later).