SCSI Technology Black Box Corp. Dave Mueller International Tech Support December 2000

BB Brasil Training December History of SCSI IBM-360 Selector Channel SASI –1979 Shugart Assoc. Systems Interface Scaled down version of the IBM Interface –1981Submitted to ANSI X3T9.2 committee SCSI –X –Approved in 1986

BB Brasil Training December SCSI Generations SCSI 1 and SCSI 2 –Each version was a complete specification –Narrow bus, slow speeds SCSI (formerly SCSI 3) –SPI SCSI Parallel Interface A collection of standards Wide bus on single connector, higher speeds Makes older standards (SCSI 1, 2) and features (HVD) obsolete –SBP Serial Bus Protocol (IEEE1394) –FCP Fibre Channel Protocol (Fibre Channel) –SSA Serial Storage Architecture (IBM)

BB Brasil Training December SPI SPI (SCSI-3) –10MBps (narrow) or 20MBps (wide) –Ultra (Fast-20) is a half standard Includes SPI but up to 20/40MBps (narrow/wide) SPI-2 (Ultra2) –LVD, SCA-80, VHDCI –20/40MBps SPI-3 (Ultra3) –Makes HVD and dual-cable wide bus (SCSI2) obsolete –WIDE only –160MBytes/sec –Many technical refinements (timing, command structure)

BB Brasil Training December Single Ended vs. Differential Single Ended –Low cost –Short cable length 20 MBps, 10 MBps, 5 MBps –Most Common –Internal cables are flat ribbon Differential –Expensive –Long cable lengths HVD 25m at all speeds, LVD 12m at all speeds –Usually only on high end products (RAID array) –Internal cables must be flat twisted pair ribbon

BB Brasil Training December LVD vs. HVD HVD –Originally in SCSI 1 (differential) –Defined in SCSI 2 as HVD –Made obsolete in SPI-3 –25 Meters LVD –Defined in SPI-2 –12 meters –Backwards compatible with old SINGLE ENDED devices Bus can only function in one mode, LVD (12m) or Single Ended (1.5/3/6m) LVD Host adapter to legacy SCSI devices If any device is legacy SCSI SE, then all LVD devices function as SE only

BB Brasil Training December STA Terms

BB Brasil Training December 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. Chart and notes copied from SCSI Trade Association

BB Brasil Training December SCSI 1 5 MBytes/Second, 8 Bits wide Electrical –Single Ended Logic 1 = 0.0 to 0.5 VDC Logic 0 = 2.5 to 5.25 VDC –Differential (HVD - High Voltage Differential) Logic 1 = +Signal > -Signal Logic 0 = -Signal < +Signal

BB Brasil Training December SCSI 1 Connectors A Cable –Alternative 1 Unshielded 50 Pin, latches optional –Internal Ribbon, AMP-LATCH Shielded 50 Pin (AMPMODU) –Alternative 2 Shielded 50 Pin (External Telco, 50 pin Centronics, CHAMP)

BB Brasil Training December SCSI 2 X Defines 8, 16 and 32 bit bus Defines Fast SCSI for 10, 20 and 40 Mbytes/second Adds the high density (.050 inch) 50 and 68 pin connectors

BB Brasil Training December SCSI 2 Connectors A Cable –Alternate 1 Unshielded HD 50 pin, no hardware Shielded HD 50 pin with latches –Alternate 2 Unshielded LD, no hardware (50 pin ribbon) Shielded LD with latches (50 Pin Centronics)

BB Brasil Training December SCSI 2 Connectors B Cable –Carries only high bytes A cable required for low bytes & termpwr –Unshielded HD 68 pin, no hardware –Shielded HD 68 pin, latches

BB Brasil Training December SCSI 3 X3T10 Committee A collection of substandards SCSI Parallel Interface (SPI) –Extension of SCSI 2 Serial –Fibre Channel –Serial Bus Protocol 2 (IEEE ) –IBM SSA (Serial Storage Architecture)

BB Brasil Training December SCSI 3 Ultra2 and Wide Ultra2 –40M and 80MByte/sec Ultra3 –160MByte/sec

BB Brasil Training December SCSI 3 Connectors P Cable –Unshielded HD 68 pin, no hardware –Shielded HD 68 pin, 2-56 screws –Carries control and 16 bits of data Q Cable –Same connectors as the P Cable –Used for high bytes in 32 bit systems P cable required for low bytes & termpwr

BB Brasil Training December Interconnections Narrow to Wide –Terminate high bytes Do NOT mix single ended and differential Do NOT mix HVD and LVD Customer must know their application See warning in AMP SCSI Guide

BB Brasil Training December SCSI Connectors SCSI 1 –Internal: 50 Pin IDC Ribbon –External: Centronics SCSI 2 –Includes SCSI 1 –Adds MD50 for external (MD for Micro D) SCSI 3 –Includes SCSI 1 and 2 –Adds MD68 for external (screw locks) and internal (no locks) SPI-2 –Adds VHDCI (Very High Density 68 pin) for external

BB Brasil Training December Black Box Products Cables and Terminators –Dead-end and pass through –High Line –Active, passive, forced perfect Differential ALWAYS passive, LVD is intelligent terminator Adapters –Does customer need adapter or High Line Terminator? Converters –SE to HVD, SE or HVD to Fiber Optic Repeaters Switches Host Adapters –IC510C is ISA, all others are PCI

BB Brasil Training December Host Adapters MD68 16LVDUltra280IC515C IDC50 MD68 16SEWide Ultra40IC514C 2xIDC50 2xMD68 1xMD6816SEWide Ultra40IC513C IDC50MD508SEUltra20IC512C IDC50MD508SEFast10IC511C IDC50 DB25 (Mac) 8SEFast10IC510C Int ConnExt ConnBus WidthSE/DiffSCSI Max Speed Mbytes/S

BB Brasil Training December Web Sites T10 Committee Website SCSI Trade Association