|'''#FD0F''' || Status Register || Command Register
|}
{| class="wikitable"
|+ Mandatory ATA1 Commands
! Command !! Code !! FR !! SC !! SN !! CY !! DH
|-
| Execute drive diagnostic || 90h || || || || || D*
|-
| Format track || 50h || * || y || y || y ||
|-
| Initialize drive parameters || 91h || || y || || || y
|-
| Read long (w/retry) || 22h || || y || y || y || y
|-
| Read long (w/o retry) || 23h || || y || y || y || y
|-
| Read sector(s) (w/retry) || 20h || || y || y || y || y
|-
| Read sector(s) (w/o retry) || 21h || || y || y || y || y
|-
| Read verify sector(s) (w/retry) || 40h || || y || y || y || y
|-
| Read verify sector(s) (w/o retry) || 41h || || y || y || y || y
|-
| Recalibrate || 1xh || || || || || D
|-
| Seek || 7xh || || || y || y || y
|-
| Write long (w/retry) || 32h || * || y || y || y || y
|-
| Write long (w/o retry) || 33h || * || y || y || y || y
|-
| Write sector(s) (w/retry) || 30h || * || y || y || y || y
|-
| Write sector(s) (w/o retry) || 31h || * || y || y || y || y
|}
'''Legend:'''
* '''FR:''' Features register used
* '''SC:''' Sector count register used
* '''SN:''' Sector number register used
* '''CY:''' Cylinder registers used
* '''DH:''' Drive/head register used
** '''y:''' The register contains a valid parameter for this command. For DH, 'y' means both drive and head parameters are used.
** '''D:''' Only the drive parameter is valid (head parameter ignored).
** '''D*:''' Addressed to drive 0 but both drives execute it.
** '''*:''' Maintained for compatibility.
== See also ==