7.12 Addressing of HDD registers
The host addresses the drive through a set of registers called a Task File. These registers are mapped
into the host's I/O space. Two chip select lines (-CS0 and -CS1) and three address lines (DA00–02) are
used to select one of these registers, while a -DIOR or -DIOW is provided at the specified time.
The chip select line -CS0 is used to address the Command Block registers while the -CS1 is used to
address Control Block registers.
The following table shows the I/ O address map.
–CS0
–CS1
DA02
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
1
0
1
0
Figure 47. I/O address map
DA01
DA00
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
1
1
0
1
1
1
Travelstar 32GH/30GT/20GN hard disk drive specifications
–DIOR = 0 (Read)
Command Block Registers
Data Reg.
Error Reg.
Sector count Reg.
Sector number Reg.
Cylinder low Reg.
Cylinder high Reg.
Drive/Head Reg.
Status Reg.
Control Block Registers
Alt. Status Reg.
Drive address Reg.
58
–DIOW = 0 (Write)
Data Reg.
Features Reg.
Sector count Reg.
Sector number Reg.
Cylinder low Reg.
Cylinder high Reg.
Drive/Head Reg.
Command Reg.
Device control Reg.
–