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SCSI Standards
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See tables at the end of this help file for definitions of several features of SCSI standards.
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Your choices are...
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SCSI-1
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SCSI-1, the original SCSI, was standardized by ANSI in 1986. It allows asynchronous data transfer rates of 1.5 MB/sec and synchronous transfer rates to a maximum of 5 MB/sec. It has an 8-bit SCSI port that uses Single-ended open-collector drivers. Uses a 50-pin connector. SCSI-1 is an obsolete standard after the development of SCSI-2.
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Wide SCSI
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This term is generally applied to Wide (16-bit) SCSI with a fast data transfer rate of up to 10 MBps.
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Fast SCSI
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Standard defined in SCSI-2. Increases the maximum data rate from 5 MBps for Narrow (8-bit) SCSI to 10 MBps.
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Wide Fast SCSI
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This term is generally applied to Wide (16-bit) SCSI with a fast data transfer rate of up to 20 MBps.
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Ultra SCSI
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This is also known as Fast-20. It doubles the FAST SCSI data rate to up to 20 MBps for the 8-bit bus
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Wide Ultra SCSI
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Wide Ultra SCSI defines a maximum transfer data rate up to 40 MBps for the Wide (16-bit) SCSI.
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SCSI-2
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SCSI-2 has significant improvements over SCSI-1 including faster data transfer rates, better connectors, wider bus path, better reliability via synchronous negotiation and parity checking. SCSI-2 has a data transfer rate from 5 MB/sec to 10 MB/sec. This speed change is called Fast SCSI-2. Also, SCSI-2 provides the option to double the bus from 8 bits to 16 bits. This change is known as Wide SCSI. By combining the Fast SCSI-2 with the Wide SCSI bus a maximum data rate of 20 MB/sec can be achieved.
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Ultra2 SCSI
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This is also known as Fast-40. It doubles the Ultra SCSI data rate to up to 40 MBps for the 8-bit bus.
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Wide Ultra2 SCSI
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Wide Ultra2 SCSI defines a maximum data rate of 80 MBps for the Wide (16-bit) SCSI.
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SCSI-3
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The SCSI-3 specification allows for faster transfer rate, more devices on a single chain (a maximum of 32), and also it incorporates serial connections in addition to the traditional parallel interconnect of SCSI-2. The serial interconnect of SCSI-3 incorporates three technologies: Serial Storage Architecture (SSA), Fibre Channel, and IEEE P1394. The serial transfer mode allows faster data rates, more devices per bus, simple connectors, and longer cables.
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Ultra3 SCSI (Ultra160)
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This is also known as Fast-80 or Ultra-160. It doubles the Ultra2 SCSI data rate to up to 160 MBps for the 16-bit bus.
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Ultra320 SCSI
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Defines a maximum data rate of 320 MBps for the Wide (16-bit) SCSI.
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Ultra640 SCSI
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Defines a maximum data rate of 640 MBps for the Wide (16-bit) SCSI.
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Fibre Channel
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A high-speed serial protocol for channels and networks that uses links of twisted-pair, coaxial cable or fiber optic cable. SCSI can use the Fibre Channel Arbitrary Loop (FC-AL) topology.
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Serial SCSI (FireWire®)
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A very fast bus standard that supports data transfer rates of up to 400 Mbps. FireWire is a registered trademark of Apple Computers, Inc. The standards are defined in IEEE 1394.
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Other
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Other unlisted, specialized, or proprietary SCSI standards.
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Search Logic:
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All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.
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Tables:
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Bus Width
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| Bus Width | | Width | Definition | | Narrow | Narrow SCSI is the conventional SCSI specified in the original SCSI. The bus width is 8 bits. | | Wide | Uses a data bus that is 16 bits wide. This doubling of the bus width respect to the Narrow SCSI comes at a higher cost, and it requires additional cabling and connectors. | | |
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SCSI Type
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| SCSI Type | | Type | Definition | | SCSI-1 | SCSI-1, the original SCSI, was standardized by ANSI in 1986. Allows asynchronous data transfer rates of 1.5 MB/sec and synchronous transfer rates to a maximum of 5 MB/sec. It has an 8-bit SCSI port that uses Single-ended open-collector drivers. Uses a 50-pin connector. SCSI-1 is an obsolete standard after the development of SCSI-2. | | SCSI-2 | SCSI-2 has significant improvements over SCSI-1 including faster data transfer rates, better connectors, wider bus path, better reliability via synchronous negotiation and parity checking. SCSI-2 has a data transfer rate from 5 MB/sec to 10 Mb/sec. This speed change is called Fast SCSI-2. Also, SCSI-2 provides the option to double the bus from 8 bits to 16 bits. This change is known as Wide SCSI. By combining the Fast SCSI-2 with the Wide SCSI bus a maximum data rate of 20 MB/sec can be achieved. | | SCSI-3 | The SCSI-3 specification allows for faster transfer rate, more devices on a single chain (a maximum of 32), and also it incorporates serial connections in addition to the traditional parallel interconnect of SCSI-2. The serial interconnect of SCSI-3 incorporates three technologies: Serial Storage Architecture (SSA), Fibre Channel, and IEEE P1394. The serial transfer mode allows faster data rates, more devices per bus, simple connectors, and longer cables. | | |
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Bus Speed
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| Bus Speed | | Speed | Definition | | Regular | This is the default speed of the original specifications of SCSI-1. The regular bus speed is 5 MHz. | | Fast | Fast SCSI increases the bus speed to 10 MHz. This doubling of the bus speed was defined in SCSI-2. | | Ultra | Also known as Fast-20, it is specified in SCSI-3. The bus speed of Ultra SCSI is 20 MHz. Ultra SCSI buses have a maximum transfer rate of 20 MB/sec for Narrow SCSI, and 40 MB/sec for Wide SCSI. | | |
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SCSI Standards
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| SCSI Standards | | | | | Maximum Bus Lengths (meters) | Max Devices Supported | | Protocol | Max Speed (MBps) | Bus Width (bits) | Single-ended | LVD | HVD | | | SCCI-1 | 5 | 8 | 6 | -- | -- | 8 | | Fast SCSI | 10 | 8 | 3 | -- | 25 | 8 | | Fast Wide SCSI | 20 | 16 | 3 | -- | 25 | 16 | | Ultra SCSI | 20 | 8 | 1.5 | -- | 25 | 8 | | Wide Ultra SCSI | 40 | 16 | 3 | -- | -- | 8 | | Ultra2 SCSI | 40 | 8 | -- | 12 | 25 | 8 | | Wide Ultra2 SCSI | 80 | 16 | -- | 12 | 25 | 16 | | Ultra3 SCSI (Ultra 160) | 160 | 16 | -- | 12 | -- | 16 | | Ultra 320 | 320 | 16 | -- | 12 | -- | 16 | | |
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