Ultra SCSI for desktop
PCs and servers
The Adaptec AHA--2940Ultra
and AHA-2940Ultra
Wide PCI-to-Fast SCSI
host adapters provide
a powerful
multitasking interface
between your computer's
PCI bus and SCSI devices
(disk drives,
CD-ROM drives, scanners,
tape backups, removable
media drives, etc.).
Product Details
System Environment
For Desktop PCs and Servers
Data Transfer Rate
Up to 20MB/sec
External Connectors
50-pin High Density
Internal Connectors
50-pin Standard
Bus Type
32-bit PCI
System Requirements
IBM-compatible PC-486,
Pentium, or above
Windows NT, Windows 95,
Windows 3.1, or DOS 6.0,
OS/2, UNIX or Netware
Operating System
PCI expansion slot
SCSI peripheral
Supported Protocols
SCSI-1
SCSI-2
SCSI-3
UltraSCSI
SCSI ID Numbers
Each device attached to
the host adapter, as well
as
the host adapter itself,
must have a unique SCSI
ID
number (0 to 7 for the
AHA-2940Ultra, and 0 to
15 for
the AHA-2940Ultra Wide).
We recommend that you
leave the host adapter
set
to its default setting
of SCSI ID 7.
To change the SCSI ID
on your hard disk and
other SCSI
devices, refer to the
device¡¯s documentation.
The host adapter supports
the SCSI Configured
AutoMatically (SCAM) protocol,
which assigns SCSI
IDs dynamically and resolves
SCSI ID conflicts automatically
at bootup. If your system
includes SCSI
disk drives or other devices
that support SCAM, you
do not need to manually
assign SCSI IDs to these
devices.
Most SCSI devices currently
in use, however, do not
support SCAM. The SCSI
IDs on these devices must
be set manually.
If you plan to boot your
computer
from a SCSI device attached
to the host
adapter, set the Boot
Target ID setting
in the
SCSISelect utility
to correspond to the SCSI
ID of the device you are
booting from.
SCSI Terminators
To ensure reliable communication,
the SCSI bus must
be properly terminated.
Termination is controlled
by
a set of electrical resistors,
called terminators.
Terminators
must be placed (or enabled)
at the two
extreme ends of the
SCSI bus. All devices
that lie
between the ends must
have their terminators
removed (or disabled).
Terminating the AHA-2940
Ultra
Termination on the AHA-2940Ultra
itself is controlled
by software commands via
the SCSISelecta
utility. The default setting
is Automatic, which
works
like this:
If the AHA-2940Ultra
detects that a cable is
connected
to either its internal
or external SCSI connector,
then it enables its terminators
(the
AHA-2940Ultra is at the
end of the SCSI bus).
If the AHA-2940Ultra
detects that a cable is
connected
to both its internal
and external SCSI connector,
then it disables its terminators
(the
AHA-2940Ultra lies between
the ends of the SCSI
bus).
We recommend that you
leave the AHA-2940Ultra
set to its default setting
of Automatic.
Terminating SCSI Devices
On most internal SCSI
devices the termination
setting is controlled
by a jumper or
a
switch.
On other internal SCSI
devices you must
physically remove or install
resistor module(s).
On most external SCSI
devices, a terminating
plug (a
resistor pack embedded
in a small plug) is installed
or removed to control
termination.
Installing SCSI Devices
(8-bit & 16-bit)
You can connect up to
a total of seven internal
and
external 8-bit SCSI devices
to the AHA-2940Ultra,
and
up to 15 devices (seven
8-bit internal and eight
Wide
(16-bit) internal or external
SCSI devices, or 15 Wide
internal and external
SCSI devices) to the
AHA-2940Ultra Wide.
If you purchased your
AHA-2940Ultra/2940Ultra
Wide in an Adaptec kit,
the kit includes an internal
SCSI cable that allows
you to connect up to two
internal SCSI devices
(the AHA-2940Ultra kit
includes a 50-pin internal
SCSI cable, and the
AHA-2940Ultra Wide kit
includes both a 50-pin
and
a 68-pin internal SCSI
cable). If you are connecting
more than two internal
SCSI devices, you must
obtain an internal SCSI
cable with enough connectors
to accommodate all of
your devices.
When Fast SCSI devices
are connected to the host
adapter, the total length
of all cables (internal
and external)
must not exceed 3 meters
(9.8 ft.) to ensure
reliable operation. If
no Fast SCSI devices are
connected,
the total length of all
cables must not exceed
6 meters (19.7 ft).
Connecting Internal
SCSI Devices
If you are connecting
internal SCSI devices,
make
sure you have an internal
SCSI cable with enough
connectors to accommodate
all of your devices.
1) Prepare each SCSI
device for installation;
configure
the device SCSI ID and
terminators (terminate
the last internal device
attached to the cable).
2) Install the SCSI device
in your computer.
3) Plug the connector
at one end of the internal
SCSI
cable into the host adapter¡¯s
internal SCSI
connector.
Make sure the colored
stripe on one side of
the
cable is aligned with
pin-1 of the host adapter¡¯s
connector. Pin-1 of
the connector is usually
designated
by a small triangle (s),
or a ¡°1¡±
on the
connector.
4) Plug the remaining
connectors on the cable
into
the connectors on the
backs of the devices.
Make sure the colored
stripe on the cable is
aligned with pin-1 of
the device¡¯s
connector.
5) Connect a DC power
cable (from your computer¡¯s
power supply) to the power
connector on
the SCSI device.
Connecting External
SCSI Devices
If you are connecting
external SCSI devices
to your
host adapter, you must
obtain an external SCSI
cable
for each external device
you install.
1) Prepare each SCSI device
for installation; configure
the SCSI ID and attach
a terminating plug into
the last external device.
2) Plug the connector
at one end of the external
SCSI
cable into the host adapter¡¯s
external SCSI
connector.
3) Plug the connector
at the other end of the
cable to
either one of the SCSI
connectors on the external
SCSI device.
4) To connect other external
SCSI devices, daisychain
each device to the previous
device until all
external SCSI devices
have been connected.
Troubleshooting Checklist
If you have a problem
during installation, check
these items first:
Have you installed the
host adapter into a PCI
Rev 2.0 compliant computer?
Are all SCSI devices powered?
Are all SCSI bus cables
and power cables properly
connected? Is pin 1 oriented
correctly?
Does the host adapter
and all devices on the
SCSI
bus have unique SCSI IDs?
Are all devices on the
SCSI bus terminated
properly?
Does your system CMOS
setup require you to
enable PCI bus parameters?
If so, see your
computer¡¯s
documentation. Check that
IRQ
channel assignment, board,
and BIOS settings
have been made.
Did you install your host
adapter in a bus master
PCI slot? Refer to your
computer¡¯s
documentation
or try another slot.
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