Funny thing is I have 4 drive set as D1: switching them on or off as needed but... the rest of the stack is doubled up as 1050 describes... using one of each pair switched on the other off, to further complicate it and to the complete loss of reasoning function of young ones... I switch them around using the BB, MIO, drive re assignment and sometime the logical re assignments within certain DOS versions. At that point the on lookers lose cohesive thought, start looking at the screen mouth breathing and looking like a skull garden...