Wang 2200 - Error Correcting Code

$
FORMAT DISK
General
Form:
$
FORMAT DISK platter [file
#
[ disk-address
Purpose
:
Tlie
$FORMAT DISK statement issues
a command to the disk
processing unit
to
format
the
specified disk platter.
This statement
can only
be used
with
Wang disk units that support
formatting under
software control
(e.g..
Models
2260C>
2260BC, and
2280/2280N)
.
Formatting
on certain
2200 disks
(e.g..
Model
2270A)
is initiated
by pressing the
format
button located on the disk unit.
CAUTION
Formatting
a
disk platter overwrites
all
data
previously
stored
on
the
platter. To
prevent the
accidental
formatting of the wrong disk
platter, it is recommended
that the Wang supplied format utility
be used.
The $F0RMAT DISK statement is available in 2200VP
BASIC-2 Release
1.9,
2200MVP
BASIC-2 Release
1.7,
and subsequent releases.
Examples of valid syntax:
10
$FORMAT DISK T/310
20 SFORMAT DISK T/Dll
30
$FORMAT DISK R#2
2.7 ERROR
CORRECTING CODE
(ECC)
As was mentioned in Section
1.5,
the Error
Correction Code is written
on
a
sector
along with
data
for
data
integrity
purposes. This
means that if
a
sector develops a "bad spot"
or hole,
the
data (up to
12
bits) in that
hole
will
be
reconstructed by the ECC on
a
read
operation. This
takes
approximately 12 seconds. If the hole is larger than 12
bits an error
(196)
will
occur.
Error correction is not
done on
a
VERIFY operation. Thus,
an
occasional VERIFY will indicate the integrity
of
a
platter and
a
possible
indication of
reformatting
the platter. (A FOIUIAT operation
assigns an
alternate sector for a sector that has a hole.)
18