A SCSI Standard Information



SCSI Standard

The 1.05 Gbyte disk drive is a SCSI (Small Computer Systems Interface) device. An external SCSI cable is required from the SCSI connector on the SBus Expansion Subsystem to the SCSI connector on the computer system. (This information applies only to the SBus Expansion Subsystem. It does not apply to computer systems.)

SCSI Bus

A bus is a signal route to which several parts of a computer system may be connected so that signals can be passed between them. The total length of a SCSI bus includes:

The maximum SCSI bus length is 6 meters (236.2 inches). This means the total length of the internal and external cables of your computer system and all of your devices and external cables connected to one SCSI bus cannot exceed
6 meters.

You can connect additional SCSI buses to your computer system by adding an SBus card which provides an additional SBus port (bus) into the SBus slots of the computer system or SBus Expansion Subsystem. Table A-1 lists the SCSI bus length of cables and devices.

    Table A-1 Table of SCSI Bus Lengths

Devices and Cables SCSI Bus Length
Meters Inches Devices (internal cable): SBus Expansion Subsystem 0.6 24.0 SPARCstation 1, and 2 0.5 19.7 SPARCstation 1+ 0.6 23.6 SPARCstation IPC and IPX 0.5 19.7 SPARCstation SLC and ELC 0.2 7.9 SPARCstation 10 0.9 32.0 SPARCclassic and SPARCstation LX 0.7 27.6 External Storage Module 1.0 39.4 Desktop Storage Pack 0.0 0.0 Desktop Storage Module 0.3 11.8 Cables (external cable): SCSI Expansion Pedestal 2.0 Desktop Storage Module Cable 0.8 31.5 Desktop Storage Pack Cable 0.8 31.5 External Storage Module Converter Cable 2.0 78.7
ESM to CPU or other SCSI devices (such as
Desktop Storage Pack or Desktop Storage Module)

For example, if you have a SPARCstation 2 (0.5 meter internal cable length), a Desktop Storage Pack (0.0 meter internal cable length plus an 0.8 meter external SCSI cable), a Desktop Storage Module (0.3 meter internal cable length plus a 0.8 meter external SCSI cable) and an SBus Expansion Subsystem with 2 disk drives (0.6 meter internal cable length and a 0.8 meter external SCSI cable, this totals 3.8 meters which is under the 6 meter SCSI bus length maximum.

Note - To compute the SCSI bus length of your system configuration, you must know the length of every external SCSI cable. The 0.8 meter external SCSI cable for the SBus Expansion Subsystem used in the previous example is an example only. Several external SCSI cable lengths are available for the SBus Expansion Subsystem.