HP 220mx HP SureStore 300mx/600mx/700mx Optical Jukebox User's Guide - Page 85

Transfer Rates on the Bus, Termination

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Operating This Jukebox on a SCSI Bus A Brief Overview of SCSI To use this form of addressing, however, the jukebox application software, the SCSI bus drivers and the host adapter firmware all have to support this mode of addressing. The following diagram shows LUNs assigned to devices within the device at ID 6. Operation on a SCSI Bus Transfer Rates on the Bus Initially, the SCSI specification defined a 5 MB/s synchronous data transfer rate on the narrow bus. SCSI now also defines "Fast" which is 10 MB/s on a narrow bus and 20 MB/s on a wide bus. Another definition is "Ultra," also known as "Fast-20" which is 20 MB/s transfer rate on a narrow bus and 40 MB/s on a wide bus. Termination To keep signals on the SCSI bus from being reflected, "terminators" must be placed at each end of the physical bus. These terminators may be either active or passive. Passive termination is a resistor network. Active termination uses a voltage regulator (the active component) to regulate the power of the resistor network to provide more stable termination. Active termination is always preferred over passive termination. Depending on your SCSI device, termination is supplied by a using a physical connector, by flipping a dipswitch, or by selecting the termination setting in software. Appendix B B- 4

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Appendix B
B-4
Operating This Jukebox on a SCSI Bus
A Brief Overview of SCSI
Operation on a
SCSI Bus
To use this form of addressing, however, the jukebox application software, the SCSI
bus drivers and the host adapter firmware all have to support this mode of
addressing. The following diagram shows LUNs assigned to devices within the
device at ID 6.
Transfer Rates on the Bus
Initially, the SCSI specification defined a 5 MB/s synchronous data transfer rate on
the narrow bus. SCSI now also defines "Fast" which is 10 MB/s on a narrow bus and
20 MB/s on a wide bus. Another definition is "Ultra," also known as "Fast-20"
which is 20 MB/s transfer rate on a narrow bus and 40 MB/s on a wide bus.
Termination
To keep signals on the SCSI bus from being reflected,
“
terminators
”
must be placed
at each end of the physical bus. These terminators may be either active or passive.
Passive termination is a resistor network. Active termination uses a voltage regulator
(the active component) to regulate the power of the resistor network to provide more
stable termination. Active termination is always preferred over passive termination.
Depending on your SCSI device, termination is supplied by a using a physical
connector, by flipping a dipswitch, or by selecting the termination setting in
software.