2.5 Disc Format
The disc format
Is
flexible and supports either 256, 512
or
1,024 bytes
per sector.
2.5.1
Formatting and Defect Management
Media defects are identified and recorded on the disc during the
manufacturing process. This defect map is used during formatting and
enables the drive to bypass these defects. During the formatting opera-
tion, the
controller uses the sector-slip technique
to
reassign defective
sectors.
Sector-slip
allows any sector with a defect to be mapped and bypassed.
The
next
contiguous
sector
Is
given
that
sector
address.
The
ST125N/138N/157N support the following three variations of the format
command:
•
Format
using a
combined
list
of
previously
defined
defects
(manufacturer's list plus user-defined list)
•
Format with previously defined list plus additional user-defined defects
• Format with manufacturer's list only (removes all user-defined defects)
2.5.2 Sector Interleave
The ST125N/138N/157N support user-specified sector interleaves of
from 1 to 1 (sectors formatted
sequentially on the disc) through the num-
ber of sectors per track minus one. This gives the user the ability to con-
figure
the drive for maximum performance within
the
operating
environment.
2.6 Diagnostics
At power-on the ST125N/138N/157N will execute a series
of
diagnostic
tests. Any failure will be indicated by a series of LED flashes. The first
failure
will be preserved. Any power-up failure will result in sense code
20H
Invalid. The drive is ready to read/write if no error codes are received
within
25
seconds. The failure codes and the test sequence follow:
ST125N/138N/157N Product Manual, Rev. C
17
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