2.2.3 Connecting the SCSI Peripherals

SCSI bus connections to the SYM8953U host adapter inside your computer can be made with an unshielded 68 conductor Ultra SCSI PVC ribbon cable (see Figure 2.3). The lead connected to pin 1 on the cable is marked with a colored stripe. The connectors on this cable may also be keyed to ensure proper pin-1 connection.

All external SCSI bus connections to the SYM8953U host adapter are made with high quality shielded 68 conductor cables (see Figure 2.3). The connectors on this cable are always keyed to ensure proper pin-1 connection.

Note: All the cables shown in Figure 2.3 are included in the Symbios Adapter Board Kit for the SYM8953U host adapter.

Table 2.1

SCSI Bus Widths and Speeds

 

 

 

 

 

 

SCSI Bus

SCSI Bus Speed

 

 

Maximum Data Rate,

STA Terms

Width, Bits

Mbytes/s

 

 

 

 

SCSI-1

 

8

5

 

 

 

 

Fast SCSI

 

8

10

 

 

 

Fast Wide SCSI

16

20

 

 

 

 

Ultra SCSI

 

8

20

 

 

 

Wide Ultra SCSI

16

40

 

 

 

 

Ultra2 SCSI

 

8

40

 

 

 

Wide Ultra2 SCSI

16

80

 

 

 

Note: Absence of the word “Wide” means an 8-bit bus width. It is

acceptable to use the word “Narrow” to avoid ambiguity.

 

 

 

 

You can connect up to eight SCSI, Fast SCSI, and Ultra SCSI devices on a SE Ultra SCSI bus only if they are evenly spaced on a 1.5-meter Ultra SCSI cable (0.19 m between devices).

Detailed Installation Procedure

2-7

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LSI SYM8953U manual Connecting the Scsi Peripherals, Scsi Bus Widths and Speeds