Dsu Controls And Indicators - HP 7925D Service Manual

7925
and head alignment. In addition, a meter is provided for
measuring radial head alignment. In the manual mode,
the state of each of the control bus lines and tag bus lines
is displayed on LED's.
Instructions for using the D8U for alignment and adjust-
ment are provided in section III of this manual and an
off-line checkout procedure in which the D8U is used is
provided in section IV.
2-8. DSU CONTROLS AND INDICATORS. The
following paragraphs describe the controls and indicators
for the D8U (figure 2-2).
Toggle switches - Twenty toggle switches that are used
for seek, alignment, and manual functions of the D8U. For
Maintenance
alternate and incremental seek operations, the switches
are divided into two groups of 10 switches each. Each
group is used
to
select a cylinder address in binary form
for alternate seek operations. For the incremental seek
operations, only the bottom 10 switches are used for select-
ing cylinder addresses.
The center column of placarded information relating to
the switches includes VFY, H8 (Cll), H4, H2, and HI, and
832, 816, 88, 84, 82, and 81. The VFY function is not used
for the HP 7925. The labels H8 (Cll), H4, H2, and HI are
used with the head alignment and manual functions. The
toggle switches select the desired data head in binary
form.
REF 7300-11
Figure 2-2. DSU Test Module, Controls and Indicators
2-5