The controller
is an RK11.
The disk drives are RK02, RK03, RK05.
The RK02 is a 1.2MB drive (256B per sector).
The RK03 is a 2.4MB drive (512B per sector).
The RK05 is a 2.4MB drive (512B per sector).
There was also a RK05F which used a fixed platter (in the same
plastic enclosure as the removables if I remember correctly). That was
double capacity, around 5MB.
Yes, the RK05J is the removable one, as described above. The RK05F is
the fixed version that doubles the density. However, to the system, it
appears as two separate drives, not as a single 5MB drive. I am not
sure how the data were interleaved between the two "logical drives"
which is important when scheduling seeks on the logical drives.
James Markevitch