5.2 Logical Interface
[Diagnostic code]
X’01’: No Error Detected.
X’02’: HDC Register Compare Error
X’03’: Data Buffer Compare Error.
X’05’: ROM Sum Check Error.
X’80’: Device 1 (slave device) Failed.
Error register of the master device is valid under two devices (master and slave) configuration. If the slave device fails, the master device posts X’80’ OR (the diagnostic code) with its own status (X’01’ to X’05’).
However, when the host system selects the slave device, the diagnostic code of the slave device is posted.
(3) Features register (X’1F1’)
The Features register provides specific feature to a command. For instance, it is used with SET FEATURES command to enable or disable caching.
(4) Sector Count register (X’1F2’)
The Sector Count register indicates the number of sectors of data to be transferred in a read or write operation between the host system and the device. When the value in this register is X’00’, the sector count is 256.
When this register indicates X’00’ at the completion of the command execution, this indicates that the command is completed succefully. If the command is not completed scuccessfully, this register indicates the number of sectors to be transferred to complete the request from the host system. That is, this register indicates the number of remaining sectors that the data has not been transferred due to the error.
The contents of this register has other definition for the following commands;
INITIALIZE DEVICE PARAMETERS, SET FEATURES, IDLE, STANDBY and SET MULTIPLE MODE.
(5) Sector Number register (X’1F3’)
The contents of this register indicates the starting sector number for the subsequent command. The sector number should be between X’01’ and [the number of sectors per track defined by INITIALIZE DEVICE PARAMETERS command.
Under the LBA mode, this register indicates LBA bits 7 to 0.
