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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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