Mitsubishi Electric M4853 Maintenance Manual page 40

8.3 Error Detection and Correction
8.3.1 Write Errors
If an error occurs during a write operation, it can be
detected by performing a read operation on the diskette
immediately following the write operation.
generally called a write check, which is an effective
means of preventing write errors.
therefore, that a write check be made without fail.
If a write error occurs, repeat the write operation and
conduct a write check.
written even after the write operation
about ten times, perform a read operation on another
track
correctly.
defective.
other track, the drive is assumed to have some trouble.
If the diskette is defective, replace it.
8.3.2 Most data errors that occur are soft errors.
error occurs,
data.
The following are possible main causes of soft errors:
o Dust is caught between the read/write head and
diskette causing temporary fault in head contact.
Such
cleaning wiper of the jacket,
recovered
read/write is continued for a long time in a very
dusty environment, however, hard errors can result
from a damaged diskette surface.
o Random electrical noise ranging in time from a few
microseconds to a few milliseconds can also cause
read.errors.
regulator,
switching
noise ratio, and increases the number of re-read
operations for data recovery.
therefore,
levels of the DC power supplies to the drive and
frame grounding.
o Written data or diskettes may have so small
defect
during write operation.
o F i n g e r p r i n t s
d i s k e t t e
f o r e i g n m a t t e r i s l e f t on a w r i t t e n d i s k e t t e f o r a
l ong ti me,
to determine whether
If so, a specific track of the diskette is
If data cannot be correctly read on the
repeat the read operation to recover the
dust is generally
by the
Spike noise generated by a switching
p a r t i c u l a r l y
intervals,
to make an adequate check on the noise
as cannot
or ot he r
can a l s o
i t can adhere to the d i s k e t t e ,
It is recommended,
If data cannot be correctly
the d ata can be
removed
and the data is
next re-read operation.
one that
deteriorates
It is necessary,
be detected by a data
f o r e i g n mat t er
c a us e a t e mp o r a r y
This is
is repeated
read
If a read
by the s e l f ­
If
has short
the signal-to-
a
check
on a w r i t t e n
e r r o r . I f
p o s s i b l y