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Each IDE
interface in the
computer can
support a
maximum of two
devices attached
to that
interface. When
connecting two
drives to a
single IDE
cable, there are
no terminators
or is any
particular order
for connecting
the drives.
However, when
two devices are
installed, one
must be
configured as
"master" and the
other as
"slave".
Configuration of
IDE drives is
done with a
jumper located
somewhere on the
drive. The
positions of the
jumpers may not
be indicated
near the jumper
pins, although
most
manufacturers
add
documentation
somewhere on the
drive.
When installing
a second IDE
hard drive in
your system, you
may have to
adjust settings
on the existing
drive to allow
it to work with
the new drive.
For example,
many Western
Digital Caviar
drives can have
a jumper in one
of four
different
positions. These
drives typically
document jumper
positions for
Master (MA),
Slave (SL), and
Cable Select
(CS). What they
do not always
show is a fourth
position that
the drive ships
in, sometimes
identified as
Single-drive
Master. The
fourth position
could be
described as
"Master, no
slave present",
while the
position
identified as
"MA" would be
for "Master,
slave present".
Some early
Seagate drives
required a
second jumper to
be added only if
a slave is
present. If you
get the
positions of the
jumpers wrong,
the system will
not detect the
drive, and may
not boot.
Three different
IDE hard drives,
all configured
as Master. The
center drive is
a Western
Digital drive
configured as a
Master (single
drive) as
shipped. To make
it a Master with
a second drive
attached, the
jumper must be
moved to a
position similar
to the bottom
drive (also a
Western Digital
drive).
If the drive
does not have
the jumper
positions
identified, read
any
documentation
that may have
been included
with the drive,
or contact the
manufacturer for
the
configuration
information.
Most
manufacturers
have
documentation
available for
download,
printing or
on-line viewing
available on
their website.
This is
especially
useful when
replacing or
adding drives to
older systems.
Connecting two
IDE drives.
When adding a
second drive,
configure one as
master (MA) and
the other as
slave (SL).
Attach the IDE
cable to both
drives and to
the system board
or IDE interface
card. Make sure
that the red
stripe is
towards pin 1 in
all cases. If
the connector on
the cable is
keyed, it will
only fit one
direction. Most
drives will have
pin one closest
to the power
connector. Look
for one of
several
identifiers to
verify this
position. The
manufacturer may
silk-screen the
number "1" next
to the
appropriate end
of the IDE
connector. There
may be a small
triangle shaped
mark on the
drive connector
and on the IDE
cable connector.
More difficult
to find, the pin
1 solder pad on
the circuit
board where the
IDE connector
attaches, may be
square in shape,
while the others
are round.
Configure one
drive as master,
and the other as
slave. In this
image, the WD
drive on the
bottom is
configured as
Master, while
the top drive
has its jumper
in the slave
position.
Other Issues:
Incompatibility
between drives:
If the system
hangs, or fails
to detect both
hard drives at
startup, try
reversing the
master and slave
configurations.
Some brands of
drive may not be
compatible with
others, or may
only work in one
configuration.
UDMA
support:
Most current
drives support
UDMA 66 for
high-speed data
transfer. To
take advantage
of UDMA 66
support, your
system must
support the
transfer mode,
you must use a
special 80-wire
IDE cable, and
both drives on
the cable should
support the
high-speed mode.
If any of these
conditions are
not met, the
system may
generate a
warning, or drop
the transfer
speed to a lower
rate.
UDMA 66 cables
have 80 wires
and usually have
a blue 40-pin
connector on one
end. The extra
wires are
grounded to help
minimize
interference. |
