SCSI (Small Computer System Interface)

Terms and Terminology

STA Terms Sustain/Burst Bus Speed, (MB/s) Bus Width, (bits) Connector

Max Bus Lengths, (Meters)(1)

Max Device Support
Single- ended LVD HVD
SCSI-1(2) 2.5/5 8 50 6 12(3) 25 8
Fast SCSI(2) 5/10 8 50 3 12(3) 25 8
Fast Wide SCSI 10/20 16 3 12(3) 25 16
Ultra SCSI(2) 10/20 8 1.5 12(3) 25 8
Ultra SCSI(2) 10/20 8 3 - - 4
Wide Ultra SCSI 20/40 16 - 12(3) 25 16
Wide Ultra SCSI 20/40 16 1.5 - - 8
Wide Ultra SCSI 20/40 16 3 - - 4
Ultra2 SCSI(2,4) 20/40 8 -(4) 12 25 8
Wide Ultra2 SCSI 40/80 16 -(4) 12 25 8
Ultra3 SCSI(6) or Ultra160 /160 16 -(4) 12 -(5) 16
Ultra320 SCSI /320 16 -(4) 12 -(5) 16
SSA 40/80 16 -(4) 12 -(5) 16
FC-AL

Notes:

(1) The listed maximum bus lengths may be exceeded in Point-to-Point and engineered applications.

(2) Use of the word "Narrow", preceding SCSI, Ultra SCSI, or Ultra2 SCSI is optional.

(3) LVD was not defined in the original SCSI standards for this speed. If all devices on the bus support LVD, then 12-meters operation is possible at this speed. However, if any device on the bus is singled-ended only, then the entire bus switches to single-ended mode and the distances in the single-ended column apply.

(4) Single-ended is not defined for speeds beyond Ultra.

(5) HVD (Differential) is not defined for speeds beyond Ultra2.

(6) After Ultra2 all new speeds are wide only.


References


Today's Date:
Last Modified:
K. Scott Rowe