Specifications

AM-6060 Network Server AMB98-07 Page
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10
SCSI Busses
As explained earlier, the AM-6060 Network Server is equipped with two SCSI busses: the 50-pin
SCSI bus and the 68-pin Wide SCSI bus. Each bus originates at a connector on the main processor
board. A flat cable runs from the bus connector to SCSI devices inside the chassis.
• A 50-conductor SCSI cable is furnished when the AM-6060 is ordered as part number
SBC-06060-00. This is the same type of SCSI cable used in our Eagle systems, in Roadrunner
030 and 040 systems, and in the AM-4000.
• A 68-conductor Wide SCSI cable is furnished when the AM-6060 is ordered as part number
SBC-06060-01.
The two bus cables are mutually exclusive. That is, the SCSI devices in the system must all be
connected to the 50-pin SCSI bus, or all to the 68-pin Wide SCSI bus. Mixes, with some devices
on one bus and some on the other, are not supported. Table 2 opposite summarizes the
characteristics of the two busses.
If You Order a Narrow SCSI System (SBC-06060-00):
An AM-6060 in the narrow SCSI configuration supports our familiar SCSI-2 disk drives (part
number PDB-00436-XX), tape streamers, DATs, and other narrow SCSI peripherals.
The system will also accept Wide SCSI devices. Examples include Fast-Wide SCSI-2 disks, such as
our PDB-00440-XX 2.1GB and 4.3GB drives, and the 26GB ¼-inch cartridge tape streamer. Each
such device requires a PDB-00440-90 Adapter to mate with the 50-pin SCSI cable. In this
environment, Fast-Wide devices will perform at about the same speed as narrow SCSI-2 devices.
If You Order a Wide SCSI System (SBC-06060-01):
For maximum system throughput, order the AM-6060 in the Wide SCSI configuration. Data moves
in and out of the disk buffers faster because the interface to the system is 16 bits wide, instead of the
8-bit path used in SCSI-2 drives. The Wide SCSI bus cable provides 68-pin connectors that mate
directly with the 68-pin connectors on Fast-Wide SCSI-2 devices.
The Wide SCSI bus also accommodates Ultra SCSI disk drives. With present AM-6060 hardware
and software, Ultra SCSI drives provide the same performance as Fast-Wide SCSI-2 disk drives.
When you order a Wide SCSI AM-6060, you’ll also need to order a PDB-00440-91 Adapter for
each narrow SCSI-2 device, such as a 525MB or other prior model tape streamer. The adapter is a
50-to-68-pin width-changer that lets narrow devices connect to the wide bus.
Inefficient to Mix Wide and Narrow Disk Drives
It is technically feasible to connect a mix of SCSI-2 disk drives and Fast-Wide SCSI-2 disk drives
to the Wide SCSI bus. A performance penalty is paid, however, because the relatively long time-on-
the-bus for the SCSI-2 disks keeps the Fast-Wide disks off the bus that much longer. To get the full
benefit of Wide SCSI, use Wide SCSI disks exclusively.