* Disable interrupts
        DIN
* Reset the disc controller
        SELP    A,:A4
* Start the transfer.
        SST     :A0             Skip if idle
        JMP     $-1
        CEA     CB,X            X := @CB
        OUT     X,:A0
* Wait for transfer to finish
?       SST     :A0             Skip if done
        JMP     $-1
* Enter bootstrap
        JMP     0

* Control block to read block 0
CB      DATA    4               Opcode (read)
        DATA    0               Unit
        DATA    0               Cyl
        DATA    0               Head
        DATA    0               Sector
        DATA    256             Word count
        DATA    0               Memory address
        DATA    0               No interrupts
        DATA    0               Next IOB

* Wasted slots to receive transfer status
        DATA    0
        DATA    0
        DATA    0

        END


