Alpha Microsystems AM-649 Manual de instrucciones descargar pdf (Pagina 9)

Page 6 Installation Instructions: AM-650 1/4" Streaming Tape Drive

PDI-00650-00, Rev. A00

Internal SCSI Bus Termination

If you are not using external SCSI termination, you may terminate the SCSI bus by enabling the

termination resistors on the last SCSI device—the one farthest away from the SCSI controller. For best

termination and most reliable SCSI performance,

this device should be at the actual physical end of the

SCSI cable

. If the SCSI cable extends beyond the device which provides termination, even if there are

no more devices attached, termination will not be as reliable as it would be if the actual end of the cable

was terminated. As mentioned above, because of its high performance, the AM-650 is more sensitive to

termination issues than earlier tape drives.

Be sure that

only the last SCSI device

has its on-board termination enabled. If more than one

device on the SCSI bus has its termination enabled, your system will probably perform

erratically! This is true whether the last device is in the computer chassis or in a separate

subsystem chassis.

If the AM-650 is the last device on the SCSI cable, and you are not using an external terminator, you

should enable termination by installing the ENTERM jumper on the back of the drive, as shown in

Figure 1.

TERMINATION POWER

To control SCSI bus termination properly, a termination power source must be provided;

this is

especially important when using an external terminator.

Why is Termination Power so important when using an external terminator?

Any terminator must have a power source. Because an external terminator does not have its own source

of power, it must get its termination power from the SCSI bus. If termination power is not available on

the bus, the external terminator cannot do its job, which means your SCSI bus will not be terminated

properly. This may result in a computer that won't boot, or that "hangs" frequently. As mentioned above,

the AM-650 is more sensitive to improper termination than were older tape drives.

All AMOS computers using the SCSI-2 or Wide SCSI-2 bus should be configured to supply termination

power

via the host controller

. When SCSI bus termination power is supplied by the host controller, no

SCSI peripheral should supply termination power to the bus.

SCSI subsystems attached to the main system should not have any additional devices supplying

termination power to the SCSI bus. Termination power should be supplied by the SCSI controller only!

For information on how to configure terminator power on SCSI hard disks and other magnetic tape

peripherals, see the following documents:

•

Each SCSI disk drive shipped by Alpha Micro has a one-page notice with jumper configuration

information, including instructions on configuring termination power.

• AM-62X SCSI 1/4" Streaming Tape Drive Installation Instructions

, PDI-00625-00, revision A07

or later.

• AM-647, 648, and 649 Digital Audio Tape (DAT) High Capacity Tape Drive Installation

Instructions

, Rev. A01 or later.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 ... 22 23

Comentarios a estos manuales

Sin comentarios

Alpha Microsystems AM-649 Manual de instrucciones Pagina 9

Comentarios a estos manuales