TABLE 1 - ATA Register Names


CS1FX (CS0): Address
Read 
Write
6
Alternate Status
 Control
7
obsolete not used
obsolete not used

 
CS3FX (CS1): Address
Read
Write
0
Data Register
Data Register
1
Error
Feature
2
Sector Count
Sector Count
3
LBA Low (Sector Number)
LBA Low (Sector Number)
4
LBA Mid (Cylinder Low)
LBA Mid (Cylinder Low)
5
LBA High (Cylinder High)
LBA High (Cylinder High)
6
Device (Drive/Head)
Device (Drive/Head)
7
Status
Command

Note: Sector Number, Cylinder Low, Cylinder High, and Drive/Head are the register names for pre-LBA drives.