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INTERNAL TRIM ERASE
The drive provides the control signals neces-
sary for proper trim erasure of data.
INDUSTRY STANDARD INTERFACE
CO MPATI B ILITY
T he drive is compatible w it h c ont r ollers th at
use an industry standard interface.
ACTIVITY INDICATOR
An activity indicator, located on the front
p anel, is automatically i l l u m i n a ted when t h e
d rive i s s elected. T hi s f r on t p a ne l L . E .D . i s
also used as an indicator in the diagnostic
mode.
DIRECT DRIVE, BRUSHLESS D. C.
MOTOR
The spindle m o t o r i s a cr y s t a l c o n t r o l l ed,
direct drive, brushless D. C. motor for
improved m otor start time, and speed
accuracy.
COMPACT SIZE
The reduced size of the drive occupies only
o ne-half t h e m o u n t i n g s p ace r equired fo r a
conventional drive.
DISKETTE LEVER LOCK SOLENOID
The diskette l ever l ock solenoid is controlled
by the host system.
1.4 F U NCTIONAL DESCRIPTION
The drives are fully self-contained, and
r equir e
n o ope r a t o r i n t e r v e n t io n d u r i n g
n ormal o p erati on. E ac h d r i v e c o n sists o f a
direct drive, spindle system, a head positioning
system, and a read/write system.
T he T M 8 4 8-1E i s
T M848-2E i s a
difference b e t w een
number of heads. The circuit board is identical
for both models.
When th e d i sk ette l ever i s opened, access is
p rovided for t h e i n s ertion of a d i s k e t te. Th e
diskette's j a cket i s
plastic guide r a i ls. It s l ocation i s ensured by
the back stop and disk ejector.
C losing
t h e di s k e t t e l e v e r ac t i v a t e s t h e
c one/clamp
s y s t em , r e s u l t i n g in
c entering and clamping of th e di skette to th e
d rive hub. The d r iv e hu b i s d r i ve n a t a
s tant
s p e e d o f 360 RPM
controlled, direct drive, brushless D. C. motor.
The h ea d
i s l o a de d i n t o c o n t ac t w i t h t h e
r ecording
m e d i u m wh e n e ve r t he di s k e t t e
lever is latched.
The heads are positioned over the desired
track by means of a stepper motor/band
assembly and i t s a ssociated electronics. This
positioner uses a 3.6 degree rotation to cause a
one track linear movement.
When a
w r i t e - protected di skett e i s i n s e rt ed
into th e d r i ve , th e W r i t e P r o t ect sensor di s-
ables the write electronics of the drive, and a
Write Protect status output signal is available
t o th e i n t e r f a ce. W he n p e r f o r m in g a w r i t e
o peration, a
0 . 0 13-inch w i de , n o m i n al , d a t a
t rack i s r e corded. Then, thi s t r ac k i s t u n n e l
erased to 0.012-inch, nominal.
Data recovery electronics include a l ow-level
r ead
a m p l i f i e r , f i l t e r , d i f f e r e n t i a t or , z e r o
crossover detector, and digi t i z in g c i r cu i ts. No
data-clock separation is provided.
In addition, the drive is supplied with th e fol -
lowing sensor systems:
1 . A
T r a c k 0 s e n so r d e t e cts w h e n t h e
Head/Carriage Assembly is positioned
over Track 0.
2. Th e T M 8 4 8-2E has tw o i n dex sensors,
e ach consisting o f a n
1-2
a s i n g l e-sided d r i ve. T h e
d o u b le-sided dr i ve. Th e on l y
t h e t w o d ri v e s i s t h e
a c cur ately p o si ti oned by
acc u r a t e
by
a cry st a l -
i n f r a r e d L . E .D .
c o n -
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