IBM IC25N020ATDA04 - Travelstar 20 GB Hard Drive - 11.0 General Operation Descriptions

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.
Device control Reg.
Alt. Status Reg.
0
1
1
0
1
Control Block Registers
Command Reg.
Status Reg.
1
1
1
1
0
Drive/Head Reg.
Drive/Head Reg.
0
1
1
1
0
Cylinder high Reg.
Cylinder high Reg.
1
0
1
1
0
Cylinder low Reg.
Cylinder low Reg.
0
0
1
1
0
Sector number Reg.
Sector number Reg.
1
1
0
1
0
Sector count Reg.
Sector count Reg.
0
1
0
1
0
Features Reg.
Error Reg.
1
0
0
1
0
Data Reg.
Data Reg.
0
0
0
1
0
Command Block Registers
DIOW- = 0 (Write)
DIOR- = 0 (Read)
DA00
DA01
DA02
CS1-
CS0-
Figure 52. I/O address map
Travelstar 48GH, 30GN & 15GN hard disk drive specifications
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