Changes
/* FDC Command Table (15 commands) */
|-
| command byte 0 || MT || MF || SK || 1 || 0 || 0 || 0 || 1
|-
| command byte 1 || colspan="5" style="text-align: center;" | x || HD || colspan="2" style="text-align: center;" | US
|-
| command byte 2 || colspan="8" | C: cylinder number
|-
| command byte 3 || colspan="8" | H: head number
|-
| command byte 4 || colspan="8" | R: sector number
|-
| command byte 5 || colspan="8" | N: bytes per sector
|-
| command byte 6 || colspan="8" | EOT: end of track (ie. last sector in track)
|-
| command byte 7 || colspan="8" | GPL: gap 3 length
|-
| command byte 8 || colspan="8" | STP: scan test (1=scan contiguous, 2=scan alternate)
|-
| Execution || colspan="8" | Data compared between the FDD and main-system
|-
| result byte 0 || colspan="8" | ST0: status register 0
|-
| result byte 1 || colspan="8" | ST1: status register 1
|-
| result byte 2 || colspan="8" | ST2: status register 2
|-
| result byte 3 || colspan="8" | C: cylinder number
|-
| result byte 4 || colspan="8" | H: head number
|-
| result byte 5 || colspan="8" | R: sector number
|-
| result byte 6 || colspan="8" | N: bytes per sector
|}
{| class="wikitable"
|+ Scan Low or Equal (19h)
|-
! !! D7 !! D6 !! D5 !! D4 !! D3 !! D2 !! D1 !! D0
|-
| command byte 0 || MT || MF || SK || 1 || 1 || 0 || 0 || 1
|-
| command byte 1 || colspan="5" style="text-align: center;" | x || HD || colspan="2" style="text-align: center;" | US
|-
| command byte 2 || colspan="8" | C: cylinder number
|-
| command byte 3 || colspan="8" | H: head number
|-
| command byte 4 || colspan="8" | R: sector number
|-
| command byte 5 || colspan="8" | N: bytes per sector
|-
| command byte 6 || colspan="8" | EOT: end of track (ie. last sector in track)
|-
| command byte 7 || colspan="8" | GPL: gap 3 length
|-
| command byte 8 || colspan="8" | STP: scan test (1=scan contiguous, 2=scan alternate)
|-
| Execution || colspan="8" | Data compared between the FDD and main-system
|-
| result byte 0 || colspan="8" | ST0: status register 0
|-
| result byte 1 || colspan="8" | ST1: status register 1
|-
| result byte 2 || colspan="8" | ST2: status register 2
|-
| result byte 3 || colspan="8" | C: cylinder number
|-
| result byte 4 || colspan="8" | H: head number
|-
| result byte 5 || colspan="8" | R: sector number
|-
| result byte 6 || colspan="8" | N: bytes per sector
|}
{| class="wikitable"
|+ Scan High or Equal (1Dh)
|-
! !! D7 !! D6 !! D5 !! D4 !! D3 !! D2 !! D1 !! D0
|-
| command byte 0 || MT || MF || SK || 1 || 1 || 1 || 0 || 1
|-
| command byte 1 || colspan="5" style="text-align: center;" | x || HD || colspan="2" style="text-align: center;" | US
*MT = Multi-track (continue multi-sector function on other head)
*MF = MFM mode(1 = Double Density)
*SK = Skip deleted-data address mark (set if sectors with deleted DAM shall be skipped)
*HD = Head number select
