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DISK DRIVE OPERATION
6.3.2 I/O Register - Address
Communication to or from the drive is through an I/O register that routes the input or output data to or from
registers addressed by a code on signals from the host (CS1FX-, CS3FX-, DA2, DA1, DA0, DIOR- and
DIOW-).
The Command Block registers are used for sending commands to the drive or posting status from the drive.
The Control Block registers are used for drive control and to post-alternate status. Table 6-3 lists these
registers and the addresses that select them.
CS1FX-
CS3FX-
N
N
N
A
N
A
N
A
N
A
A
N
A
N
A
N
A
N
A
N
A
N
A
N
A
N
A
N
A
N
A
N
A
N
N
N
* Mapping of registers in LBA mode.
Logic conventions are:
A = signal asserted
N = signal negated
X = don't care
48
Table 6-3 I/O Port Function/Selection Address
Address
DA2
DA1
DA0
Control Block Registers
X
X
X
0
X
X
1
0
X
1
1
0
1
1
1
Command Block Registers
0
0
0
0
0
1
0
1
0
0
1
1
0
1
1
1
0
0
1
0
0
1
0
1
1
0
1
1
1
0
1
1
0
1
1
1
X
X
X
Functions
READ(DIOR-)
WRITE(DIOW-)
High Impedance
Not Used
High Impedance
Not Used
High Impedance
Not Used
Alternate Status
Device Control
Device Address
Not Used
Data
Data
Error Register
Features
Sector Count
Sector Count
Sector Number
Sector Number
* LBA bits 0-7
* LBA bits 0-7
Cylinder Low
Cylinder Low
* LBA bits 8-15
* LBA bits 8-15
Cylinder High
Cylinder High
* LBA bits 16-23
* LBA bits 16-23
Drive/Head
Drive/Head
* LBA bits 24-27
* LBA bits 24-27
Status
Command
Invalid Address
Invalid Address
SpinPoint V40 Product Manual
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