HP 220mx HP SureStore 220mx Optical Jukebox User's Guide - Page 85

Single-ended, High-Voltage Differential, and, Low-Voltage Differential Interfaces

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Operating This Jukebox on a SCSI Bus A Brief Overview of SCSI SCSI and This Jukebox [1] Terminator - device required on each end of a SCSI bus to prevent reflected signals [2] SCSI Device - a device on the internal SCSI bus [3] Host Bus Adapter - SCSI bus connecting point [4] Host Internal - SCSI components internal to the host computer [5] External - SCSI components external to the host computer [6] SCSI Device - SCSI device external to the host computer Single-ended, High-Voltage Differential, and Low-Voltage Differential Interfaces The SCSI bus is electrically implemented in three ways: single-ended, high-voltage differential, and low-voltage differential. These terms come from the way the signals are asserted on the bus. Single-ended buses use a 5-volt signal that is referenced to ground. This method makes the bus somewhat susceptible to noise and loss of signal quality over distance. The maximum allowable length of a single-ended SCSI bus was initially 6 meters (19.7 feet). Fast SCSI required the maximum length of the bus to be reduced to 3 metres (9.8 feet). High-voltage differential buses uses two lines for each signal and Appendix B B- 5

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Appendix B
B-5
Operating This Jukebox on a SCSI Bus
A Brief Overview of SCSI
SCSI and This Jukebox
[1] Terminator - device required on each end of a SCSI bus to prevent reflected
signals
[2] SCSI Device - a device on the internal SCSI bus
[3] Host Bus Adapter - SCSI bus connecting point
[4] Host Internal - SCSI components internal to the host computer
[5] External - SCSI components external to the host computer
[6] SCSI Device - SCSI device external to the host computer
Single-ended, High-Voltage Differential, and
Low-Voltage Differential Interfaces
The SCSI bus is electrically implemented in three ways: single-ended,
high-voltage differential, and low-voltage differential. These terms come
from the way the signals are asserted on the bus.
Single-ended buses use a 5-volt signal that is referenced to ground. This
method makes the bus somewhat susceptible to noise and loss of signal
quality over distance. The maximum allowable length of a single-ended
SCSI bus was initially 6 meters (19.7 feet). Fast SCSI required the
maximum length of the bus to be reduced to 3 metres (9.8 feet).
High-voltage differential buses uses two lines for each signal and