1.5Single-Ended and Differential SCSI Buses

The SCSI standard defines two electrical buses:

￿Single-ended bus

￿Low-voltage differential bus

1.6Maximum Cable Length for SCSI Standards

Table 1.1 lists the maximum SCSI cable length and number of disk drives that you can use, depending on the SCSI speeds and type of device.

Table 1.1

Maximum Cable Length for SCSI Standards

 

 

 

 

 

 

 

Single Ended

Low-Voltage

Maximum # of

Standard

 

SCSI

Differential SCSI

Drives

 

 

 

 

 

Ultra SCSI

 

1.5 m

12 m

7

 

 

 

 

 

Ultra SCSI

 

3 m

12 m

3

 

 

 

 

Wide Ultra SCSI

 

12 m

15

 

 

 

 

Wide Ultra SCSI

1.5 m

12 m

7

 

 

 

 

Wide Ultra SCSI

3 m

12 m

3

 

 

 

 

 

Ultra 2 SCSI

 

 

25 m

1

 

 

 

 

 

Ultra 2 SCSI

 

 

12 m

7

 

 

 

 

Wide Ultra 2 SCSI

 

25 m

1

 

 

 

 

Wide Ultra 2 SCSI

 

12 m

15

 

 

 

 

Ultra160 SCSI

 

25 m

1

 

 

 

 

Ultra160 SCSI

 

12 m

7

 

 

 

 

Wide Ultra160 SCSI

 

25 m

1

 

 

 

 

Wide Ultra160 SCSI

 

12 m

15

 

 

 

 

 

Ultra320

 

 

12 m

15

 

 

 

 

 

Ultra320

 

 

20 m

1

 

 

 

 

 

Single-Ended and Differential SCSI Buses

1-3

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