$1C00/7168/VIA2+0:   Data Port B (SYNC, Motors, Bit Rates, LED)

   +----------+---------------------------------------------------+
   | Bit  7   |   0 = SYNC found                                  |
   | Bits 6-5 |   Bit rates (*):                                  |
   |          |     00 = 250000 Bit/s    01 = 266667 Bit/s        |
   |          |     10 = 285714 Bit/s    11 = 307692 Bit/s        |
   | Bit  4   |   Write Protect Sense: 1 = On                     |
   | Bit  3   |   Drive LED: 1 = On                               |
   | Bit  2   |   Drive Motor: 1 = On                             |
   | Bit  1-0 |   Step motor for head movement:                   |
   |          |     Sequence 00/01/10/11/00... moves inwards      |
   |          |     Sequence 00/11/10/01/00... moves outwards     |
   +----------+---------------------------------------------------+
   (*) Usually used: %11 for Tracks  1-17
                     %10 for Tracks 18-24
                     %01 for Tracks 25-30
                     %00 for Tracks 31-35

ROM-Reference:

 AND $1C00  : $C103
 BIT $1C00  : $F562 $FB39 $FB3E $FB46 $FB67
 EOR $1C00  : $D6AE
 LDA $1C00  : $EA86 $EB25 $EC3F $EC77 $F355 $F380 $F57A $F982 $F9A2 $F9E8
              $FA6E $FADB $FB00 $FBBB
 LDX $1C00  : $FA34 $FA65
 ORA $1C00  : $C11B $C13C $D6C8 $EA77
 STA $1C00  : $C113 $C11E $C13F $D6B1 $D6CB $EA8B $EB2A $EC98 $F260 $F35C
              $F385 $F987 $F9ED $FA75 $FAE0 $FEEA