Chapter 1
General Information
Introduction
This
chapter
contains a general description of the 9895A Flexible Disc Memory
and
a
description of the recording formats which can
be
used.
General Description
The 9895A Flexible Disc Memory
is
a
random
access storage system employing a flexible
magnetic medium.
It
consists of a controller printed circuit module, two drive modules, a
power
supply
and
the
chassis
and
cover package. The 9895A can
be
ordered
in various
optional configurations, which delete the controller,
one
drive or
the
controller
and
one
drive.
The controller module accepts
and
interprets
commands
over the Hewlett-Packard Interface
Bus (HP-IB), controls the interface to the drive electronics module, retrieves
and
stores
data
from the drive electronics module,
and
returns disc drive
and
disc operation status informa-
tion to the host mainframe.
Each drive module contains all the mechanical parts for physically handling the disc. These
include the drive spindle
and
motor, the
read/write
and
erase
heads, write protect
and
Single-sided disc sensors, door
open/
closed sensor,
door
lock
and
various gUides. Each
drive module also contains all driver, positioning, loading
and
interface electronics
needed
by the mechanical parts. The electronics
are
located on a printed circuit
board
mounted
on
the
bottom
of the drive module.
The
power
supply module contains rectifiers, filters
and
regulators to provide
+24
volts,
+ 12 volts,
+5
volts
and
-12
volts to the various electronic modules.
An
internal transformer provides
stepped
down voltages to the
power
supply
and
120
Vac
to
the spindle motors.
The flexible magnetic medium used in the 9895A
is
called a flexible disc. The flexible disc
is
20
centimeters (7.9 inches) in diameter
and
has a
3.8
centimeter (1.5 inch) hole for align-
ment
on
the
spindle of the disc drive.
The
disc
is
enclosed in a protective Polyvinylchloride
(PVC) jacket with a slot for
head
access to the recording surface. Both sides of
the
flexible
disc
are
used
for data storage.
1-1
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