01F0-01F7 ---- HDC 1   (1st Fixed Disk Controller)   same as 017x (ISA, EISA


01F0   r/w data register

01F1   r   error register
       diagnostic mode errors:
        bit 7-3    reserved
        bit 2-1 = 001  no error detected
            = 010  formatter device error
            = 011  sector buffer error
            = 100  ECC circuitry error
            = 101  controlling microprocessor error
        operation mode:
         bit 7  = 1  bad block detected
            = 0  block OK
         bit 6  = 1  uncorrectable ECC error
            = 0  no error
         bit 5       reserved
         bit 4  = 1  ID found
            = 0  ID not found
         bit 3       reserved
         bit 2  = 1  command completed
            = 0  command aborted
         bit 1  = 1  track 000 not found
            = 0  track 000 found
         bit 0  = 1  DAM not found
            = 0  DAM found (CP-3022 always 0)

01F1   w   WPC/4  (Write Precompensation Cylinder divided by 4)

01F2   r/w sector count
01F3   r/w sector number
01F4   r/w cylinder low
01F5   r/w cylinder high

01F6   r/w drive/head
        bit 7   = 1
        bit 6   = 0
        bit 5   = 1
        bit 4   = 0  drive 0 select
            = 1  drive 1 select
        bit 3-0      head select bits

01F7   r   status register
        bit 7 = 1  controller is executing a command
        bit 6 = 1  drive is ready
        bit 5 = 1  write fault
        bit 4 = 1  seek complete
        bit 3 = 1  sector buffer requires servicing
        bit 2 = 1  disk data read successfully corrected
        bit 1 = 1  index - set to 1 each disk revolution
        bit 0 = 1  previous command ended in an error

01F7   w   command register
       commands:
        98 E5   check power mode   (IDE)
        90  execute drive diagnostics
        50  format track
        EC  identify drive     (IDE)
        97 E3   idle           (IDE)
        95 E1   idle immediatete   (IDE)
        91  initialize drive parameters
        1x  recalibrate
        E4  read buffer        (IDE)
        C8  read DMA with retry    (IDE)
        C9  read DMA without retry (IDE)
        C4  read multiplec     (IDE)
        20  read sectors with retry
        21  read sectors without retry
        22  read long with retry
        23  read long without retry
        40  read verify sectors with retry
        41  read verify sectors without retry
        7x  seek
        EF  set features       (IDE)
        C6  set multiple mode  (IDE)
        99 E6   set sleep mode     (IDE)
        96 E2   standby        (IDE)
        94 E0   standby immediate  (IDE)
        E8  write buffer       (IDE)
        CA  write DMA with retry   (IDE)
        CB  write DMA with retry   (IDE)
        C5  write multiple     (IDE)
        E9  write same     (IDE)
        30  write sectors with retry
        31  write sectors without retry
        32  write long with retry
        33  write long without retry
        3C  write verify       (IDE)
        9A  vendor unique      (IDE)
        C0-C3   vendor unique      (IDE)
        8x  vendor unique      (IDE)
        F0-F4   EATA standard      (IDE)
        F5-FF   vendor unique      (IDE)