There is a problem with SIO2SD together with my 1050. Or maybe I'm just stupid 
1050 is set as D1: because I want to boot from some old disks.
SIO2SD does not react if SIO2SD D1 is empty and I can boot from a floppy, so no problem at all.
But If I boot from SIO2SD and then remove the disk image from SIO2SD's D1 and add another to D2, SIO2SD does not respond anymore. The 1050 keeps responding as D1.
So how is it possible to boot selectively from Sio2SD (as D1) and then read Disks from 1050 (as D1) and copy them to SIO2SD (with empty disk image in D2)?
When 1050 is set as D2 it works as intended, but I can't boot floppy disks then.
I tried fiddling around with SIO2SD settings like TopDrive and Device ID. This had no effect, what do these settings mean? Why to set a device ID when SIO2SD can handle all devices anyway?