Fujitsu MHS2030AT - 2.5" Notebook 30GB Drive Product Manual page 131

At command completion (I/O registers contents to be read)
1F7 (ST)
H
1F6 (DH)
H
1F5 (CH)
H
1F4 (CL)
H
1F3 (SN)
H
1F2 (SC)
H
1F1 (ER)
H
(18) EXECUTE DEVICE DIAGNOSTIC (X'90')
This command performs an internal diagnostic test (self-diagnosis) of the device.
This command usually sets the DRV bit of the Drive/Head register is to 0
(however, the DV bit is not checked). If two devices are present, both devices
execute self-diagnosis.
If device 1 is present:
Both devices shall execute self-diagnosis.
The device 0 waits for up to 6 seconds until device 1 asserts the PDIAG-
signal.
If the device 1 does not assert the PDIAG- signal but indicates an error, the
device 0 shall append X'80' to its own diagnostic status.
The device 0 clears the BSY bit of the Status register and generates an
interrupt. (The device 1 does not generate an interrupt.)
A diagnostic status of the device 0 is read by the host system. When a
diagnostic failure of the device 1 is detected, the host system can read a status
of the device 1 by setting the DV bit (selecting the device 1).
When device 1 is not present:
The device 0 posts only the results of its own self-diagnosis.
The device 0 clears the BSY bit of the Status register, and generates an
interrupt.
Table 5.6 lists the diagnostic code written in the Error register which is 8-bit code.
If the device 1 fails the self-diagnosis, the device 0 "ORs" X'80' with its own
status and sets that code to the Error register.
C141-E171-03EN
Status information
x x x DV
Max. cylinder [MSB]/Max. LBA
Max. cylinder [LSB]/Max. LBA
Max. sector/Max. LBA [LSB]
xx
Error information
5.3 Host Commands
Max head/LBA [MSB]
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