Addressing Of Hdd Registers; Figure 52. I/O Address Map - IBM IC25N020ATDA04 - Travelstar 20 GB Hard Drive Specifications

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

Figure 52. 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
Travelstar 48GH, 30GN & 15GN 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.
63
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.