Data General 6662, Клиентская документация

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Installing the Drive
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Table 1 Specifications for the Model 6662, 6796 and 6799 Disk Drive
Specification Model 6796 Model 6662
Model 6799
Unformatted capacity 609 Mbytes 498 Mbytes
Formatted capacity 520 Mbytes 339 Mbytes
Interface SCSI-2 SCSIĆ1, singleĆended
6796 = singleĆended
6799 = differential
Number of disk surfaces 11 7
Number of cylinders 1,429 1,780
Number of sectors 63.5 (average) 54
Bytes per sector 512 512
Current draw
+5V dc (+ 5%) Typical 1.0 A Typical 1.0 A
Maximum 1.0 A Maximum 1.0 A
+12V dc (+5%) Typical .75 A Typical .75 A
Maximum 2.5 A Maximum 2.5 A
Power dissipation
Idle Typical 11 watts Typical 11 watts
Positioning Maximum 14 watts Maximum 14 watts
NOTE: The environmental specifications for the disk drive meet or exceed those of the
Data General computer system in which you install this disk drive. Refer to your
computer system documentation for the environmental specifications.
The singleĆended and the differential drive have no operational differences between
them. The only functional difference is that the differential drive can use a much
longer SCSI cable and therefore, can be physically located further from the CPU than
a singleĆended drive. For example, the maximum length of a singleĆended SCSI bus is
slightly less than 20 feet, while a differential SCSI bus can be 82 feet long. You can use
the singleĆended model as a terminator resistor in a daisyĆchain configuration, while
the differential model does not have this capability.
NOTE: Never install differential and singleĆended drives on the same SCSI bus.
The SCSI bus signals and terminators differ.
You can distinguish between the drives by their size, printedĆcircuit board layout, and
their 118 numbers. The 118 numbers are on a label on the bottom side (the side
without the printedĆcircuit board) of the drives. Figure 2 shows the single-ended and
differential models.