Connecting External Scsi Devices; About Scsi - Yamaha A4000 Owner's Manual

Connecting external SCSI devices

This section explains how to connect external devices such as external hard disk drives, MO drives, or CD-
ROM drives.

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.
The A5000/A4000SCSI interface allows convenient connection of internal and/or external hard disk
drives, MOD drives, CD-ROM drives, and other SCSI-compatible devices. Up to 7 devices can be con-
nected to the SCS "bus," including an internal SCSI drive.
Most external SCSI devices have two SCSI terminals, allowing a number of devices to be "chained"
together. Devices chained together in this can normally be connected in any order. The last device in
the chain must be "terminated," either with a terminator unit plugged into the open SCSI connector, or
by turning the device's internal terminator on (if available). The first device in the chain must also be
terminated, but in the case of the A5000/A4000 this can be accomplished either with the terminator
switch on the main circuit board, or the terminator switch/jumper on an internal hard disk unit.
When an internal hard disk is installed
A5000/
Internal HD
A4000
Main Unit
Circuit Board
When an internal hard disk is not installed
A5000/
A4000
Main Unit
Circuit Board
• Before connecting SCSI devices, be sure to turn off the power of the A5000/A4000 and all connected
equipment. If the power is on while connections are being made, the A5000/A4000 or SCSI devices
can be damaged.
• Including the A5000/A4000, 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 cor-
rectly. When shipped from the factory, the A5000/A4000 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.
• Don't forget to attach a terminator to the last SCSI device 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.
• Use as short a SCSI cable as possible. Using long cables can cause unreliable operation. (In general,
the total cable length including the cables inside the A5000/A4000 should be less than 6 meters
(approximately 18 feet).)
• Use good-quality SCSI cables. Poor-quality cables can cause unreliable operation.
• Hard disks, MO disks, and other removable media will be formatted by the A5000/A4000. If you wish to
use a hard disk, MO disk, or other removable media that was being used by a computer, you will need
to perform the format operation after connecting and powering-on the disk.
• Some SCSI devices have only one SCSI connector. If you are using such a device, connect it at the
end of the daisy-chain.
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.)
External SCSI External SCSI
device device
Factory default
External SCSI External SCSI
device device
Important
Installing Optional Equipment
External SCSI
device
External SCSI
device
A5000/A4000 •
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Appendix