SCSI stands for Small Computer System Interface. It is a family of standards governing how computers and peripheral devices exchange commands and data—not the name of one universal cable or connector.
What SCSI defines
SCSI standards specify interfaces, functions, operations, and command behavior so conforming computers and devices can interoperate. The term can refer to the command and architectural rules, as well as to the original physical interface; which meaning applies depends on context.
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The standards separate those layers. For example, SAM-5 provides a reference model for common SCSI device behavior and the structure of SCSI I/O implementations (IEC’s SAM-5 entry).
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SCSI began as both a protocol and a parallel physical interface. The protocol is now carried over several transports, including Serial Attached SCSI (SAS), Fibre Channel through FCP, and IP networks through iSCSI, as described by the Storage Networking Industry Association.
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| Term | What it refers to |
|---|---|
| Parallel SCSI | The original parallel interface and its associated protocol. |
| SAS | A serial interconnect used to carry SCSI; ISO describes its physical interconnect in ISO/IEC 14776-153:2015. |
| SPL | Rules for exchanging information between SCSI devices over a serial interconnect, as described in IEC’s SPL-3 entry. |
| FCP | The Fibre Channel transport for SCSI. |
| iSCSI | SCSI carried over IP networks. |
These terms describe different connection or transport choices, not interchangeable names for one cable. The ISO page for ISO/IEC 14776-150:2004 says that edition was last reviewed and confirmed in 2018 and remains current; that status applies to that publication, not to every historical SCSI standard or connector.
Why “SCSI” alone does not identify a connector
A SCSI label does not tell you which physical connection a particular device uses. A legacy parallel-SCSI device and a device using a newer transport may both use SCSI standards while requiring different connections. Before connecting or buying legacy hardware, check the device documentation for the interface generation, connector, bus width, and termination requirements. A cable or terminator that merely says “SCSI” is not enough to establish compatibility.
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Where the name came from
A U.S. government FIPS publication says the standards committee X3T9.2 selected the name “Small Computer System Interface” and began work at its April 1982 meeting. The publication describes the proposed standard as a formalization and extension of the earlier Shugart Associates System Interface (SASI) (FIPS PUB 131).
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That publication also gives period-specific figures: up to 25 meters for the maximum cable length of its described differential electrical option, and 3 to 4 megabytes per second for its synchronous transfer option. Those are historical design details, not current SCSI or SAS performance specifications.
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