HP 9114B Operator's Manual page 32

Technical Description of the HP 9114B BatteryLife
In order to understand how the battery lifeof the HP 9118is
affectedby the application, vouneed10understand the way the
drive's hardware works, Basically, the HP 9114's hardware canbe
in three different states. Fach of these states uses different
amounts af power. The events that cause the drive to switch fram
one state 10 anather and theamount of powerthat is consumedin
wach stateis explainedbelow
The three different states are sleep. active, andaccess. Thefirst
state, called thesleep state, 1s a very Tow power stale in which all
hardwareis shut down exceptfar the CMOS HEIL integrated
aircuit anda small wake-up c i r c u i t , Thesecondstate 1s the active
state in which all of thecontroller rcuitry and all other drive
clectromes are powered. The third state, the access state, 1s when
the flexibledisc is being accessed. This state requires extra power
to spin the motor and step the head. The approximate amount of
current drawnfromthe battery in cachstale is shown next
Sloep state milliamps (disc access light off)
Active state 350milliamps (disc access light off)
Access state 1000 milliamps (disc access light on)
The state theHP 91148is in depends upon theactivity on the HP-
TL The HP-IL integrated circuit used mn the HP 91148 determines
which HEIL commands cause the disc driveto gofromthesheep
state totheactive state. Certain commands a r e handled
automatically by the chip and somerequired that the commandbe
proceessed by the CPU onthecontraller board. his means that
power must beapplied 1othecontroller board. A detailed listof
the HP-IL messages that causethedisc drive to gofrom the sleep
stateto he active state follow
Basically, two operations cause the transitionfromsleep to active
state. Thefirst one configures the loopwith theauto addressing
command. This requires the CPLtoaccept a loop address and pass
on thenext highest address tothe next device un the Toop. The
second operationis addressing the 1H YT148 to be a talker or a
listener on the Toop
The commands sent over HPAL dependon your computer andon
the typeof operations being performed by your computer