4
AVA-1515 Installation Guide
Part Number: 510534-00, Rev. A
Print Spec Number: 492411-00
Current Date: 1/25/94
ECN Date: 2/1/94
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AA
AA
AA
AA
AA
AA
AA
AA
AA
AA
AA
AA
AA
AA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AA
AA
A
A
A
A
A
A
A
A
A
A
A
A
A
A
Caution:
AVA-1515 host adapters support
only single-ended SCSI devices. Differential
SCSI devices may be damaged if connected
to the host adapter. The peripheral docu-
mentation will tell you whether the device
is single-ended or differential.
1
Lay out the cables and find the pin-1 element of
each cable and peripheral connector.
On internal cables, pin 1 is usually marked with a
contrasting color on one edge of the ribbon cable,
and a small triangle marks pin 1 on the SCSI
connector. External cable connectors can only be
plugged-in one way, so pin-1 orientation is
automatic.
2
Attach the SCSI cable(s) to the host adapter and
the peripheral(s), using the internal and/or exter-
nal connector(s).
3
Be sure to maintain correct pin-1 orientation
throughout the bus. The AVA-1515 uses a 25-pin
DB25 external connector (Apple compatible), and
a 50-pin flat ribbon-type internal connector.
Terminating the SCSI Bus Cable
The last physical SCSI device on either end of the
SCSI bus must have a set of resistors called termina-
tors. Terminators must be removed from, or disabled
on, all other devices on the SCSI bus.
The AVA-1515 and most SCSI peripherals have built-
in terminators that can be enabled or disabled. Termi-
nate only the devices at each end of the SCSI bus.
Terminating the Host Adapter
The three factory-installed terminators on the
AVA-1515 host adapter are located below the internal
SCSI connector, as shown in the diagram on page 1.
You must remove these terminators if you attach
SCSI devices to both the internal and external SCSI
connectors, since the host adapter is then in the
middle of the SCSI bus. Terminators are 8-pin
220/330 ohms resistors.
