Table of Contents
Advertisement
Rotational
Delay
Rotational delay
is
the time required for the desired
record area
to
reach the
read/
write
head
so that
data
transfer
can
begin.
This time can range
from
zero
to
almost
a
full
revolution.
Half
a revolution
(average
rotational delay)
is
generally
used
for
timing purposes.
The
maximum
and
average
rotational
delays
for
3340/3344
drives
are:
Maximum
rotational
delay
=
20.24
milliseconds
Average
rotational
delay
=
10.12
milliseconds
Note:
Use
of
the
Rotational
Position
Sensing
feature
minimizes
the effect
of
rotational
delay
by
permitting the
drive
to
disconnect
from
the channel,
thereby
allowing use
of
other
drives
during
a
latency period.
3344
MODELS
In
the
3344
dual-drive
models, the
Read Only
func-
tion
is
controlled
by
a
switch
on
the operator panel
for
each
drive.
File
Protection
Control
of
Write
and Seek
commands
within
a
pro-
gram
can
be
affected
by
the Set
File
Mask
command.
A
description of the Set
File
Mask command
is
given
in
the
ISC and 3830-2
reference
manuals.
By
entering a Set
File
Mask,
selected
Write
and Seek
commands
can be
inhibited
even though
they appear
in
the
command
chain.
Data Transfer
Nominal
read/write
rates for
the disk drives
are:
Bytes-per-second
=
885,000
Microseconds-per-by
te
=
1.13
DATA
SECURITY
AND
PRIVACY
The 3340
and 3344 have
a
Read
Only
function.
This
function,
in
conjunction with previous
methods
such
as
File
Protect
and Seek
Verification, offer
a
means
of
limiting
access
to
data
areas of the
data module.
Read Only
Function
3340
MODELS
The Read Only
function provides the
means
for
protecting designated
data
modules from being
rewritten or erased.
Each
data
module
is
equipped with an
inset in
the
handle.
The
operator
can change
the
inset
position
before
inserting
the data
module
in
the
drive.
Note:
This
insert
is
only
accessible
when
the
data
module
is
not
on
the drive
(see
the
"Operating
Instructions"
section).
When
the
Read
Only
option
is
made, any
Write
command
addressed
to the drive
is
rejected.
Subse-
quent sense information
indicates
Command
Reject
(byte
0,
bit
0)
and Write
Protect (byte
1,
bit 6).
Seek
Verification
The 3340/3344
track
format
includes
two
bytes
in
each count
area
and
home
address (physical
address,
PA)
for
seek
verification.
When
a
count
area or
home
address
is
processed during Read,
Search, or
Clock
operations, the
bytes
are
compared
with the
most
recent
seek
address.
A
non-compare
results in
termi-
nation of the operation
at
the
end
of the
count
area or
home
address with
channel
end, device end,
and
unit
check.
Seek check
is
also
indicated
in the
sense
information.
Input/Output Operations
17
Advertisement
Table of Contents
