Service manual
4-
14
1l....
DOUBLE-DENSITY
DISK
CONTROLLER
D - GENERAL DRIVE CHECKOUT
The
purpose
of
the
General Drive Checkout is to verify
that
your
system is
reading
from
and
writing to
the
diskette properly. Each sector on
the
diskette is
written
to
and
read
from a
number
of times. Various patterns are
written
on
the
diskette to
allow
testing of
the
head
seek
mechanism
and
the
read/write
head
itself.
The
test is repeated
three
times.
Do
not
be alarmed if
this
test seems to take
an
abnormally long
time
to finish.
It
is a very
thorough
test,
and
requires from
45
minutes
to
an
hour
and
a
half
to complete.
The
duration
of
the
test will
depend
on
the
type
of
media
you
use
for
the
test.
Run
this
test
again only
if
you
encounter
problems.
While each pass is being executed,
the
program
will
print
the
letters "ABCDEFG," one
after
the
other,
at
intervals of a few
minutes.
These letters
indicate
the
various
phases
of
the
test
and
give you
an
idea of
how
far
it
has progressed.
TEST will
print
an
"END OF PASS" message at
the
end
of each pass.
There
are
two
possibilities.
If
everything proceeds normally,
the
output
for
the
pass
will
read:
ABCDEFG
END
OF
PASS
n
However, if
the
test discovers
any
problems
on
the
current
pass,
the
output
will
include
the
number
of
"hard"
(h)
and
"soft"
(s)
errors, as follows:
ABCDE
hhh/sss
FG
END
OF
PASS
n
In
this
example, test E has errors.
The
tests corresponding to each letter are:
A
= Write all zeroes
B
= Read all zeroes
C
= Write all ones
D
= Read all ones
E
= Write identification
pattern
F = Read identification
pattern
G = Random read/write test
The
number
of
"hard"
and
"soft"
errors is
indicated
by
the
numbers
"hhh"ยท
and
"sss,"
respectively. Let
the
test
run
through
all
three
passes, even
if
it discovers errors.
Soft errors
usually
indicate
that
the
disk drive temporarily
had
difficulty
reading
from or
writing to
the
diskette.
The
difficulty
may
occur because of dust, noise, static electricity,
etc. Soft errors are
nothing
to
be
concerned
about; you
may
correct
them
by
simply
repeating
the
failed process.
If
after performing
ten
retries (in
an
attempt
to correct a soft error)
the
program
still
cannot perform
the
read
or write operation, TEST reclassifies
the
soft error as a
hard
error. Hard errors
are.caused
by
malfunctions
in
the
electronic or electro-mechanical
hardware
and/or
defective diskettes.
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