L C0 Addr RDCNEXTIOCB
L C1 Addr RDCDATAPTR
L C2 Addr RDCDATAPTR
L C3 Addr RDCDATAPTR1
L C4 Addr RDCCYLINDER
L C5 Addr RDCHEADSECTOR
L C6 Addr RDCPAGECOUNT
L C7 Addr RDCCSBPTR
L C8 Addr RDCCOMPLETIONCODE
L C9 Addr RDCDISKSTATUS
R C7 Val 
L C10 Addr
MR C10 FillC