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Component
Device
selector
Table 3-3. (Continued)
Explanation
identifies the interface's select code (4, and 7 through 31) as well
as the device's primary address (HP-IB devices only). Here are
some examples of device selectors:
700
specifies select code 7 and primary address 0
(note that device selectors with HP-IB
addressing must contain 3 or 4 digits).
702
specifies select code 7 and primary address 2.
800
specifies select code 8 and primary address O.
1402
specifies select code 14 and primary address 2.
Unit number
tells the system additional information about the device's unit-
number setting. Many devices have hard-wired unit numbers,
while others use the unit number to identify different portions of
one disc. For instance, the unit number of the right drive of a
9122 is 1, while the left drive is unit 0 (note that internal drives
of Model 236 computers are numbered in the opposite order).
Volume number
identifies the volume number (multi-volume hard discs only, such
as HP 9133D,HP 9133H, and HP 9133L drives).
Examples
Here are several examples of volume specifiers (Note the": ," is not a typographic error.
If the device type is omitted, the system will determine the device type automatically):
: CS80 ,700
or
: ,700
Left drive's
volume
specifier_~~~~~~~
Cable connected to
~-----
the HP-IB interface
at select code 7.
This disc is set to
HP-IB primary address 0
(by switches on back.)
Right drive's
sticker (unit 0)
~
.....
~:...-_-volume
specifier
sticker (unit 1)
Figure 3-4. HP 9122D Volume Specifier Example
Mass Storage Concepts
3-7
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