Error Reporting; Spindle Drive System - HP 7936 Support Manual

Functional Description
7936 and 7937
Write is disabled immediately upon detection of
the error and continues to be disabled until status
is cleared. Interrupt (RWIRQ-L) is asserted at the
end of the sector in which the error occurred.
Interrupt and the status register can be cleared by
a clear command to the command register.
5-108. Data Overrun Detected. This error indi-
cates that the data transfer has not been completed
by the time SOS-L starts to go high. During a
write, this indicates that an inconsistency exists be-
tween SOS-L and
we
from the servo system, or a
hardware failure. During a read, the error probably
indicates a loss of lock by the read/write system
PLL, or the data framing word was not detected.
(A data framing word might be detected in ran-
dom data, leading to a partially transferred er-
roneous sector.)
The error occurs only at the end of a sector.
Interrupt is asserted and write is disabled until the
status register is cleared. Interrupt and the status
register can be cleared by a clear command to the
status register.
5-109. Write Holdoff Command Abort. This er-
ror indicates that the write operation was aborted
because Write Holdoff (WHO-L) was asserted at
the falling edge of SOS-L.
The error will only occur at the beginning of a
sector. Write is disabled immediately upon detec-
tion, and until the status register is cleared.
Interrupt is asserted at the end of the sector.
Interrupt and the status register can be cleared by
a clear command to the status register.
5-110. Write With Servo Error. This error indi-
cates that a write was aborted because a Servo
Error (SVER-L) was detected by the servo system.
5-
tIl.
Parity Error During a Read With Mask
Set. This error indicates that a parity error was
detected in the amplitude qualification circuitry
(probably dropout). The error is used primarily
for defect location in media test.
Read is not disabled until the next sector. Interrupt
is asserted at the end of the sector in which the
5-34
error occurred. Interrupt and the status register can
be cleared by a clear command to the status
register. This action occurs if the bit mask is not
set.
5-112. Servo Error During a Read with Mask Set.
This error indicates that a servo system off-track
error or sampled servo error occurred during the
previous read operation. This error is used
primarily for defect location for sparing.
Read is not disabled until the following sector.
Interrupt is enabled at the end of the sector in
which the error occurred. Interrupt and the status
register can be cleared by a clear command to the
command register. No action occurs if the mask bit
is set.
5-113. Underrun. This error signals that a under-
run was detected in the data operation. This indi-
cates that a read or write completed too soon rela-
tive to the rising edge of Start of Sector (SOS-L),
which marks the end of the sector.
During a read operation, the error probably indi-
cates a loss of lock by the read/write system PLL,
causing the read clock to go to a higher than nor-
mal frequency and leading to an early completion
of the data transfer.
An underrun in a write operation and in a read
operation (not caused by a PLL loss of lock)
would indicate a failure to receive SOS-L at the
proper time or an out of sync write clock. These
problems are probably related to the operation of
the servo system.
5-114. ERROR REPORTING. The read/write
system errors detailed above are reported to the
microprocessor in PCA-A6 via the read/write con-
troller status register.
5-115.
SPINDLE DRIVE SYSTEM
The principal component in the spindle drive sys-
tem is an ac induction motor which transmits its
torque to the spindle assembly via a belt drive sys-
tem. The motor is powered by the ac line voltage
input to the drive. In the standard drive (60 Hz),