IBM IC35L020 Hard Drive Specifications - Page 54

Addressing of registers, Cabling, Control Block Registers, DIOW- = 0 Write, DIOR- = 0 Read

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9.1.8 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. 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 the Control Block registers. The following table shows the I/O address map. CS0- CS1- 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 1 0 DA2 0 0 0 0 1 1 1 1 1 DA1 0 0 1 1 0 0 1 1 1 DA0 DIOR- = 0 (Read) DIOW- = 0 (Write) Command Block Registers 0 Data Reg. Data Reg. 1 Error Reg. Features Reg. 0 Sector count Reg. Sector count Reg. 1 Sector number Reg. Sector number Reg. 0 Cylinder low Reg. Cylinder low Reg. 1 Cylinder high Reg. Cylinder high Reg. 0 Drive/Head Reg. Drive/Head Reg. 1 Status Reg. Command Reg. Control Block Registers 0 Alt. Status Reg. Device control Reg. Note: "Addr." field is shown just as an example. During DMA operation (from writing to the command register until an interrupt) all registers are not accessible. For example, the host is not supposed to read the status register contents before interrupt -the value is invalid. Figure 35. I/O address map 9.1.9 Cabling The maximum cable length from the host system to the drive plus circuit pattern length in the host system must not exceed 18 inches. For data transfers greater than 8.3 MB/s it is recommended that designs measures are used to reduce cable noise and cross-talk. Examples of design modification include use of shorter cable, bus termination, and the use of shielded cable. The 80-conductor ATA cable assembly (P/N SFF-8049) must be used for systems operating at Ultra DMA modes 3, 4 and 5. Deskstar 60 GXP Hard disk drive specification 40

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9.1.8
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. 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 the 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)
DA0
DA1
DA2
CS1-
CS0-
Note: "Addr." field is shown just as an example.
During DMA operation (from writing to the command register until an interrupt) all registers are not
accessible. For example, the host is not supposed to read the status register contents before interrupt
—the value is invalid.
Figure 35. I/O address map
9.1.9
Cabling
The maximum cable length from the host system to the drive plus circuit pattern length in the host system
must not exceed 18 inches.
For data transfers greater than 8.3 MB/s it is recommended that designs measures are used to reduce
cable noise and cross-talk. Examples of design modification include use of shorter cable, bus termination,
and the use of shielded cable.
The 80-conductor ATA cable assembly (P/N SFF-8049) must be used for systems operating at
Ultra DMA modes 3, 4 and 5.
Deskstar
60 GXP Hard disk drive specification
40