HITACHI Deskstar & CinemaStar P7K500 Hard Disk Drive specification (Rev 1.1)
34
5.2.5
Addressing of registers
The host addresses the drive through a set of registers called the Task File. These registers are mapped into
the I/ O space of the host. Two chip select lines (CS0– and CS1–) and three address lines (DA0-02) are
used to select one of these registers, while a DIOR– or DIOW– is provided at the specified time.
The CS0– is used to address Command Block registers. while the CS1– is used to address Control Block
registers.
The following table shows the I/ O address map.
CS0–
CS1–
DA2
DA1
DA0
DIOR– = 0 (Read)
DIOW– = 0 (Write)
Command Block Registers
0
1
0
0
0
Data Reg.
Data Reg.
0
1
0
0
1
Error Reg.
Features Reg.
0
1
0
1
0
Sector count Reg.
Sector count Reg.
0
1
0
1
1
Sector number Reg.
Sector number Reg.
0
1
1
0
0
Cylinder low Reg.
Cylinder low Reg.
0
1
1
0
1
Cylinder high Reg.
Cylinder high Reg.
0
1
1
1
0
Device/Head Reg.
Device/Head Reg.
0
1
1
1
1
Status Reg.
Command Reg.
Control Block Registers
1
0
1
1
0
Alt. Status Reg.
Device control Reg.
Table 26 I/O address map
Note:
"Addr" field is shown as an example.
During DMA operation (from writing to the command register until an interrupt) not all registers are
accessible. For example, the host is not supposed to read status register contents before interrupt (the
value is invalid).
5.2.6
Cabling
The maximum cable length from the host system to the drive plus circuit pattern length in the host system
shall not exceed 18 inches.
For higher data transfer application (>8.3 MB/s) a modification in the system design is recommended to
reduce cable noise and cross-talk, such as a shorter cable, bus termination, or a shielded cable.
For systems operating with Ultra DMA mode 3, 4, and 5, 80-conductor ATA cable assembly shall be used.
Summary of Contents for 3.5-INCH Deskstar HDP725050GLAT80
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