SCSI Connections

SCSI Bus Differences

SCSI Bus Differences

A Small Computer Systems Interface (SCSI) bus is an IEEE standard bus for connecting your workstation to internal and external devices (SCSI devices) running at different speeds, singly or in combination. Examples of these SCSI devices are 4-mm DDS-format tape drives, CD-ROM drives, and Win- chester hard disk drives.

There are two types of SCSI buses available with this workstation - a single- ended SCSI bus, and a fast, wide differential SCSI bus. Table 16 shows the specification differences between these SCSI buses, and Table 17 shows the SCSI addresses, ID numbers, and arbitration priorities for each.

CAUTION:Do not mix single-ended and fast, wide devices on any one bus type. Doing this will

 

 

 

cause a system failure.

 

 

 

 

Table 16

 

SCSI Bus Differences

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Data Bus

Maximum

Maximum

 

Device

Controller

 

Transfer Rate

 

 

Physical

Embedded

 

 

Width

Addresses*

Cable Length

 

 

 

 

 

Location

or Plugable

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Single-Ended

 

 

 

 

 

 

 

 

 

 

8 bits

8

6.0 meters

 

Internal and

Embedded

 

Up to 5 Mbytes

 

 

 

per second

 

 

 

(19.6 feet)

 

external

 

 

 

 

 

 

 

 

 

 

 

Fast, Wide

 

 

 

 

 

 

 

 

Differential

 

16 bits

16

25 meters

 

Internal

Embedded

 

 

 

 

 

Up to 20 Mbytes

 

 

 

(82 feet)

 

and

 

 

per second

 

 

 

 

 

external

 

 

 

 

 

 

 

 

 

 

* Address 7 is reserved for host controller use on both buses.

 

 

 

 

 

 

 

 

 

 

 

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