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Feature Descriptions
6-10 Maxtor
Atlas
15K
6.17.1
DIFFSENS
The DIFFSENS signal in the SCSI bus defines the current operating mode of the
SCSI bus. A level below +.5 volts defines a single-ended bus. A level b.7
and +1.9 volts defines an LVD bus. A level above +2.4 volts defines a High Voltage
Differential (HVD) bus. Before LVD was introduced, HVD was simply called
Differential SCSI.
All single-ended-only devices connect the DIFFSENS signal to ground. On an LVD
bus, the terminators drive the DIFFSENS signal to +1.3 volts unless some device is
holding the signal at ground. HVD devices pull DIFFSENS up to +5 volts via a
resistor.
The Maxtor Atlas 15K disk drive is designed with a circuit that monitors the level of
DIFFSENS at power-on. The drive then enables the appropriate circuits for LVD or
single-ended operation, or disables its interface completely if it detects an HVD level
on DIFFSENS.
The two normal operating environments for the Maxtor Atlas 15K disk drive are an
all-LVD or (LVD/MSE) bus, in which case it operates in its LVD mode, or a bus that
contains at least one single-ended device, in which case the Maxtor Atlas 15K disk
drive operates in single-ended mode.
HVD mode is not supported by the Maxtor Atlas 15K disk drive. Signal levels on an
HVD bus can reach as high as +15 volts due to allowed common mode transients.
6.17.2
DIFFSENS SWITCHING
After establishing its initial operating mode, the Maxtor Atlas 15K disk drive
continues to monitor the DIFFSENS signal. If a change in level is detected, such as
might occur if a device is added to or removed from the bus, the DIFFSENS circuit
detects the change and presents a mode change interrupt to the drive firmware. The
operating mode of the interface switches to the new mode 100 msec after the change
is detected, providing the new level has remained constant. This delay is required to
prevent spurious mode switches due to noise on the DIFFSENS line.
CAUTION:
The LVD and HVD alternatives are mutually exclusive and
damage may occur to SCSI devices if an LVD device is
plugged into an operating HVD bus.
Содержание Atlas SCSI Drive 15K II
Страница 1: ...Maxtor Atlas 15K Product Manual ...
Страница 2: ...Maxtor Atlas 15K Product Manual April 29 2003 PN 1880 ...
Страница 6: ......
Страница 12: ...Table of Contents xii Maxtor Atlas 15K ...
Страница 14: ...List of Figures xiv Maxtor Atlas 15K ...
Страница 24: ...About This Manual 1 4 Maxtor Atlas 15K ...
Страница 53: ...Installation Maxtor Atlas 15K 3 25 Figure 3 9 Crosswise Airflow Cooling ...
Страница 54: ...Installation 3 26 Maxtor Atlas 15K ...
Страница 66: ...Specifications 4 12 Maxtor Atlas 15K ...
Страница 232: ...Feature Descriptions 6 16 Maxtor Atlas 15K ...
Страница 238: ...Appendix A A 6 Maxtor Atlas 15K ...
Страница 253: ...Glossary G 13 Maxtor Atlas 15K ...
Страница 254: ...Glossary G 14 Maxtor Atlas 15K ...
Страница 260: ...Index I 6 Maxtor Atlas 15K ...