HP 7970B Operating And Service Manual page 18

Performance Checkout
option is not present.
If
no select function is desired, the
jumper can be placed in the off position which will permit
response to controller commands, when unit is in on-line
with load sequence completed, and is not rewinding. Verify
the following conditions to check the select (CS) line:
a. Unit responds to commands with jumper connected
to OFF.
b. Unit responds to 0 through 3 positions when cor-
responding CSO through CS3 is selected by the controlling
device.
c. When front panel select option is included, place
internal jumper in the off position and verify that response
to push buttons 0 through 3 is same as in step "b" above.
When the front panel OFF pushbutton is pressed, unit must
not respond to any commands from the controlling device.
3-42. Verify that the off-line (CL) line clears the write
condition and returns the selected tape unit to the reset
condition.
3-43. MOTION COMMANDS. Verify that the following
external commands will place the selected and on-line tape
unit in the corresponding drive mode:
a. Forward (CF): Tape drives forward.
b. Reverse (CR): Tape drives reverse then stops at
load point tab.
c. Rewind (CRW): Tape unit enters rewind mode, re-
mains on-line.
d. High Speed (CH): Tape unit will respond only when
this is combined with either a forward or reverse command.
When so combined, tape will drive at 160 ips speed. CH with
CR will drive reverse past load point.
3-6
7970Bj7970C
CAUTION
Do not issue sequential fast drive commands
without allowing time to reach full speed or to
return to zero speed. Failure to observe this pre-
caution may cause excessive power dissipation
in the reel servo amplifier circuitry. Minimum
time between commands should be 1 second or
the sum of the start and stop times (whichever
is greater).
3-44. STATUS OUTPUTS. Verify that the following
status outputs are true (low assertion) when a selected and
ready tape unit is in the condition indicated.
a. On-Line (SL): True when selected tape unit has
been manually placed on-line.
b. Ready (SR): True when selected unit is on-line,
tape loading cycle is completed, and tape unit is not in re-
wind mode.
c. Load Point (SLP): True when selected tape unit
has tape positioned at the load point reflective strip.
d. Density (SD2, SD5, or SDS): Verify that selected
tape unit will display the density selected by the tape unit
density switch if this option is present. Without this option,
the tape unit will be set at SOO cpi but there will be no SDS
output.
e. Rewind (SRW): Verify that this status remains
true as long as the selected unit is in the rewind mode.
Must remain true until tape is repositioned at load point
tab.
f. File Protect (SFP): True when selected unit is not
write-enabled.
g. End-of-Tape (EOT): True when selected unit has
moved end-of-tape tab beyond photosense head. Will re-
main true until tab again passes photosense head in the re-
verse direction.
Part 2