Internal Trim Erase; Industry Standard Interface Compatibility; Activity Indicator; Direct Drive, Brushless D. C. Motor - Tandon TM848-1E User Manual

INTERNAL TRIM ERASE
The drive provides the control signals neces-
sary for proper trim erasure of data.
INDUSTRY STANDARD INTERFACE
COMPATIBILITY
The drive is compatible with controllers that
use an industry standard interface.
ACTIVITY INDICATOR
An activity indicator, located on the front
panel, is automatically illuminated when the
drive is selected. This front panel L.E.D. is
also used as an indicator in the diagnostic
mode.
DIRECT DRIVE, BRUSHLESS D. C.
MOTOR
The spindle motor is a crystal controlled,
direct drive, brushless D. C. motor for
improved motor start time, and speed
accuracy.
COMPACT SIZE
The reduced size of the drive occupies only
one-half the mounting space required for a
conventional drive.
DISKETTE LEVER LOCK SOLENOID
The diskette lever lock solenoid is controlled
by the host system.
1.4 FUNCTIONAL DESCRIPTION
The drives are fully self-contained, and
require no operator intervention during
1-2
normal operation. Each drive consists of a
direct drive, spindle system, a head positioning
system, and a read/write system.
The TM848-1E is a single-sided drive. The
TM848-2E is a double-sided drive. The only
difference between the two drives is the
number of heads. The circuit board is identical
for both models.
When the diskette lever is opened, access is
provided for the insertion of a diskette. The
diskette's jacket is accurately positioned by
plastic guide rails. Its location is ensured by
the back stop and disk ejector.
Closing the diskette lever activates the
cone/clamp system, resulting in accurate
centering and clamping of the diskette to the
drive hub. The drive hub is driven at a con-
stant speed of 360 RPM by a crystal-
controlled, direct drive, brushless D. C. motor.
The head is loaded into contact with the
recording medium whenever the diskette
lever is latched.
The heads are positioned over the desired
track by means of a stepper motor/band
assembly and its associated electronics. This
positioner uses a 3.6 degree rotation to cause a
one track linear movement.
When a write-protected diskette is inserted
into the drive, the Write Protect sensor dis-
ables the write electronics of the drive, and a
Write Protect status output signal is available
to the interface. When performing a write
operation, a 0.013-inch wide, nominal, data
track is recorded. Then, this track is tunnel
erased to 0.012-inch, nominal.
Data recovery electronics inelude a low-level
read amplifier, filter, differentiator, zero
crossover detector, and digitizing circuits. No
data-clock separation is provided.
In addition, the drive is supplied with the fol-
lowing sensor systems:
1. A Track 0 sensor detects when the
Head/Carriage Assembly is positioned
over Track
o.
2. The TM848-2E has two index sensors,
each consisting of an infrared L.E.D.