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> Распиновки SCSI, SCSI pinout
сообщение 14.6.2015, 10:09
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Какие разъемы бывают:

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The SCSI standard can be divided into SCSI1, SCSI2, SCSI wide and so on. SCSI advantages includes flexible device attachment (up to 7-15 devices per SCSI bus), support for almost any peripheral type (disk, tape, CDROM, scanner etc), greater speed. All SCSI commands can overlap with commands on other devices. SCSI is widely used in servers, but due to it cost less used in end-user computers (ATA devices are cheaper and offer comparable perfomance).

SCSI-1 (previously noted as SCSI-1 X3.131-1986 )SCSI-158540
Fast SCSI (SCSI-2 X3.131-1994)SCSI-21081080
Fast-Wide SCSISCSI-2 /
Ultra SCSI (deprecated terms Fast 20,
SCSI-3, Double-speed SCSI )
Ultra-Wide SCSISCSI-3201640320
Ultra2 SCSI (Fast 40, SCSI-3)SCSI-440840320
Ultra2-Wide SCSISCSI-4401680640
Ultra3 SCSI (Fast 80, SCSI-4)Ultra160/m40*2880640
Ultra3-Wide SCSIUltra160/m40*2161601280
Ultra4 SCSIUltra32080*281601280
Ultra4-Wide SCSIUltra32080*2163202560

Ultra3 features the same base frequency as Ultra2 (40MHz) but transmits 2 bytes per data clock thus doubling the total throughput. This is the same technique used in SDRAM, DDR and RAMBUS Memory where one data word (8 or 16 Bits) is transmitted at the raising edge and one at the falling edge. Ultra4 doubles the base frequency of Ultra2 (80MHz) and like U3 transmits 2 bytes per data clock thus doubling the total throughput vs U3. Ultra4 also features AAF (Adjustable Active Filter), QAS (Quick Arbitration and Selection). This enables these fast speeds at these long cable lengths and decreases the overall latencies due to the protocol overhead.

Fast-Wide SCSI is actually SCSI-2, however many cable manufacturers refer to the 68-pin plugs as SCSI-3.
Most SCSI 1-4, 160/m Ultra320 Devices can be mixed on the same bus, however, the slowest device/controller determines the bus speed during negatiating and in some cases also during data transfers!
You can not mix single ended and High Voltage (HV) differential! But you can mix most LVD (Low Voltage Differential) and single ended devices. Fast-Wide SCSI-2 is also sometimes called SCSI-3 (in particular when referring to the 68 HP connector).

Name Common Name Application Bus Width SCSI Standards Comment
D-Sub 25 pinAppleExternal8 narrowSCSI 1+2Primarily for Microtest Discport, ZIP drives and Apple Computers
50 pin CentronicsSCSI-1External8 narrowSCSI 1+2+3Most common for Scanners, Tapes and external CD-ROM"s and other slower periphereals
50 pin (HP)SCSI-2External8 narrowSCSI 2+3External Raid-Disks and high performance Tape Libraries
68 pin (HP)SCSI-3External16 wideSCSI 2+3External Raid-Disks and high performance Tape Libraries
50 pin ribbonnormalInternal8 narrowSCSI 1+2+3Standard internal narrow SCSI Disks, CD-ROM"s, Tapes and optical disks
68 pin ribbonwideInternal16 wideSCSI 2+3Wide SCSI Disks and other high performance drives

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