K6602637
Rev.3
02.27.01
- 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
0
1
0
0
0
Data
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
0
1
1
1
1
Status
Command
Control Block Registers
1
0
1
1
0
Alt. Status
Device Control
Invalid or Not Used
0
0
´
´
´
Invalid address
0
1
´
´
´
Data bus high impedance (not used)
1
0
0
´
´
Data bus high impedance (not used)
1
0
1
0
´
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.
