K6602705
Rev.3
08.20.01
- 31 -
6.3 Logical Interface
6.3.1 I/O Registers
Communication between the host system and the device is done through I/O registers. The Command
Block Registers are used for sending commands to the device or posting device status. The Control
Block Registers are used for controlling the device or posting device status. The registers are listed in
Table 6.3.
Table 6.3 Register List
Addresses Functions
CS0- CS1- DA2 DA1 DA0 READ(DIOR-) WRITE(DIOW-)
Command Block Registers
01000Data Data
0 1 0 0 1 Error Features
0 1 0 1 0 Sector Count Sector Count
0 1 0 1 1 Sector Number Sector Number
0 1 1 0 0 Cyl Low Cyl Low
0 1 1 0 1 Cyl High Cyl High
0 1 1 1 0 Device/Head Device/Head
01111Status Command
Control Block Registers
1 0 1 1 0 Alt. Status Device Control
Invalid or Not Used
00
´´´
Invalid address
01
´´´
Data bus high impedance (not used)
100
´´
Data bus high impedance (not used)
1010
´
Data bus high impedance (not used)
'0' is low signal level. '1' is high signal level.
6.3.1.1 Data register
A 16-bit register to be used for transferring data blocks between the HDD's data buffer and the host.
6.3.1.2 Error register
This register stores device status when the last command has been completed or diagnostic codes
when a self-diagnostic process has been completed. The contents of this register are valid when the
error bit (ERR) is set in the Status Register. The contents of this register are diagnostic codes when
the device has just completed a self-diagnostic process requested when turning on the power or
resetting.
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