Owner's Manual

Setting the SCSI Board Terminator Switch
320
Appendix
Setting the SCSI Board Terminator Switch
About SCSI
SCSI (pronounced “scuzzy”) stands for Small Computer System Interface, and is a data
transmission interface standard used by personal computers and other devices.
Hard disk drives (internal or external), MO disk drives, or CD-ROM drives which sup-
port this standard can be connected to the A3000 for use. Up to 7 SCSI devices can be
connected. (If an internal hard disk is installed, up to 6 external SCSI devices can be
connected.)
External SCSI devices usually have two SCSI connectors. These two connectors allow
you to connect multiple SCSI devices in a “daisy-chain.” The placement sequence of a
device within the daisy-chain does not matter.
The last device in the daisy chain must have a device known as a “terminator” connected
to it. (Alternatively, the terminator switch of the last device must be turned on.) A ter-
minator is also required for the first device of the daisy chain, but this is provided by the
terminator switch (or terminator jumper switch) of the internal hard disk or the SCSI
interface board itself.
When an internal hard disk is installed
indicates the terminator (or a terminator switch
that is turned on). Devices which are not indicated by
this symbol must not have a terminator attached to them.
(Alternatively, their terminator switch must be turned off.)
A3000
External SCSI
device
Internal HD
T
T
When an internal hard disk is not installed
A3000
External SCSI
device
T
T
T
External SCSI
device
External SCSI
device
External SCSI
device
External SCSI
device
SCSI interface
board
SCSI interface
board
Important
• Including the A3000, each SCSI device is distinguished by a number from 0—7, called
the SCSI ID. If two or more devices have the same SCSI ID number, the SCSI devices
will not function correctly. When shipped from the factory, the A3000 is set to SCSI
ID 6. Be aware that the SCSI ID number of a device has no relation to its position in
the daisy-chain.
• If an external SCSI device is not connected, it is not necessary to attach a terminator
to the external SCSI connector of the SCSI interface board.