IBM IC25N040ATCS04 - Travelstar 40 GB Hard Drive - 7.11 Addressing of HDD Registers

7.11 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.
–Drive address Reg.11101
Device control Reg.Alt. Status Reg.01101
Control Block Registers
Command Reg. Status Reg. 11110
Drive/Head Reg.Drive/Head Reg.01110
Cylinder high Reg.Cylinder high Reg.10110
Cylinder low Reg.Cylinder low Reg.00110
Sector number Reg.Sector number Reg.11010
Sector count Reg.Sector count Reg.01010
Features Reg.Error Reg.10010
Data Reg.Data Reg.00010
Command Block Registers
DIOW- = 0 (Write)DIOR- = 0 (Read)DA00DA01DA02CS1-CS0-
Figure 49. I/O address map
Travelstar 60GH & 40GN hard disk drive specifications
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