Installation guide
RLL
has
recently
become
popular
and
is
based
on
a
7.5
megabit
per
second
transfer
rate.
Because
of
the
higher
transfer
rate.
more
data
can
be
put
onto
a
track:
26
sectors
of
512
bytes
or
13312
bytes
per
track.
7.5
mega
bits
per
second
is 50%
faster
than
5.0
megabits
per
second.
A drive
running
MFM
might
yield
20
megabytes
and
30
if
it
can
run
RLL.
-RLL
is
similar
enough
to
MFM
so
that
no
major
redesign
of
the
drive
was
required.
Differences
however
do exist. MFM
code
uses
a Simpler
arrangement
of
three
frequencies
while RLL
uses
6.
The
drive
configuration
table
identifies
which
drives
are
MFM
or
RLL.
This
does
not
mean
an
MFM drive
will
not
run
RLL.·
MiniScribe's
warranty
for
data
reliability
of
the
drive
is
based
on
the
deSignated
encoding
method.
There
are
companies
that
buy
our
:MFM
products
and
retest
it
to
RLL
specifications.
These
companies
then
offer
their
own
warranty
for RLL
performance.
If
you
come
across
one
of
these
drives verify
that
they
do
test
to
RLL
specifications
and
that
they
warranty
their
product.
If
in
doubt
give
us
a call
at
1-
800-356-5333.
.
INTERLEAVING
During
the
initialization
of
the
drive
you
may
be
asked
for
interleave.
Interleave
refers to
the
numbering
sequences
of
the
sectors
of
information.
Typically
there
are
1 7
sectors
per
disk.
If
these
were
visible.
the
disk
would
resemble
being
sliced
into
sections
like
pie.
During
a
read
or
write
operation.
the
controller
must
collect
the
data
then
transfer
it
to
the
deSired location.
This
handling
of
data
takes
time
causing
consecutive
sectors
may
be
missed.
To
avoid
this.
the
data
can
be
recorded
or
read
in
leap
frog
fashion.
Example:
Read
1.
skip
2.
read
1.
skip
2.,
etc.·
In
this
case.
every
3rd
sector
is
read
which
represents
an
interleave
of
3 to 1 (3: 1
or
simply
3). It
also
means
that
it
will
take
3
revolutions
of
the
disk
to
read
the
entire
track.
If
the
interleave
is
too
tight:
say
1:
1.
the
neXt
sector
may
have
already
passed
under
the
recording
head
when
the
controller
is
ready
to
continue.
The
result
is
that
the
controller
will
have
to
wait
1 revolution for
that
sector
to
arrive
again.
This
pattern
continues
for
all
of
the
17
sectors
forcing
the
controller
to
wait
for
1
7
revolutions
to
read
1
track.
It
is
better
to
be
too loose
than
be
too
tight
on
interleave.
Following
is
an
interleave
table
to
better
illustrate
different
interleaves.
Typically
the
following
table
will
work:
6:1 IBM XT
4: 1
Rl1
XT
Clones
3: 1
l\1FM
AT
and
XT
Clones
2: 1
Turbo
MFM
Systems
To
determine
the
optimum
performance
will
require
_some
experimentation.
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