Difference between revisions of "Small Computer System Interface"

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'''SCSI''' (formally 'Small Computer System Interface') was a popular [[interface]] [[standard]] for high-speed devices ([[disk]]s, [[magnetic tape drive|tape drives]], [[scanner]]s, etc). It was composed of a set of standards for the various layers: physical signalling, commands, etc.
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The '''Small Computer System Interface''' (universally known by its acronym, '''SCSI''') was a popular [[interface]] [[standard]] for high-speed devices ([[disk]]s, [[magnetic tape drive|tape drives]], [[scanner]]s, etc). It was composed of a set of standards for the various layers: physical signalling, commands, etc.
  
 
Over time, a variety of options were developed for many of these; e.g. the original standard was 8-[[bit]] [[parallel]] using [[single-ended signalling]], but later versions used 16-bit with [[differential pair]]s, at a variety of speeds (mostly [[synchronous]], but one was [[asynchronous]]). Even later, a high-speed [[serial]] version was developed; and ultimately, one which worked over [[TCP/IP]] (usually over an [[Ethernet]]).
 
Over time, a variety of options were developed for many of these; e.g. the original standard was 8-[[bit]] [[parallel]] using [[single-ended signalling]], but later versions used 16-bit with [[differential pair]]s, at a variety of speeds (mostly [[synchronous]], but one was [[asynchronous]]). Even later, a high-speed [[serial]] version was developed; and ultimately, one which worked over [[TCP/IP]] (usually over an [[Ethernet]]).
  
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== SCSI Versions ==
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{| class="wikitable" style="margin:auto"
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|+ Some common SCSI Versions
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|-
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! Name !! Alternative Name !! max. Devices !! Bus Bandwidth MB/sec
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|-
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| SCSI || SCSI-1 || 8 || 5
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|-
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| Fast(-Narrow) SCSI || (Narrow) SCSI-2 || 8 || 10
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|-
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| Fast-Wide SCSI || (Wide) SCSI-2 || 16 || 20
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|-
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| Ultra(-Wide) SCSI || (Wide) SCSI-3 || 16 || 40
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|}
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{{semi-stub}}
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[[Category: Interface Standards]]

Latest revision as of 16:18, 2 December 2023

The Small Computer System Interface (universally known by its acronym, SCSI) was a popular interface standard for high-speed devices (disks, tape drives, scanners, etc). It was composed of a set of standards for the various layers: physical signalling, commands, etc.

Over time, a variety of options were developed for many of these; e.g. the original standard was 8-bit parallel using single-ended signalling, but later versions used 16-bit with differential pairs, at a variety of speeds (mostly synchronous, but one was asynchronous). Even later, a high-speed serial version was developed; and ultimately, one which worked over TCP/IP (usually over an Ethernet).

SCSI Versions

Some common SCSI Versions
Name Alternative Name max. Devices Bus Bandwidth MB/sec
SCSI SCSI-1 8 5
Fast(-Narrow) SCSI (Narrow) SCSI-2 8 10
Fast-Wide SCSI (Wide) SCSI-2 16 20
Ultra(-Wide) SCSI (Wide) SCSI-3 16 40