I General Description; Introduction; Purpose And Use Of Equipment - Control Data Corporation BR8 SERIES Hardware Maintenance Manual

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GENERAL DESCRIPTION
1.1 INTRODUCTION
The Flexible Disk Drive (FDD) is a compact, portable, random access, data storage
device that interfaces with a central processor via a control unit. Input/Output
data and control signals are transmitted by means of an
r/o
cable.
1.2 PURPOSE AND USE OF EQUIPMENT
Data, in the form of magnetized bits, is written on, or read from the tracks of a rotating
diskette. The FDD uses a single, flexible, removable diskette (one recording surface)
enclosed in a sealed jacket. The unit is capable of hard-sector or soft-sector (missing
clock) format operation, but the missing clock must be recovered externally (from the
FDD).
1.3 PRODUCT DESCRI PTI ON
The major FDD components are the spindle, disk drive motor, read/write head,
stepping motor, track indexing device, and printed circuit board.
The options include Write Protect, Data/Clock Separation, Power Reduction, Sector
Separation, Unit Select, Ready, Door Unlock, Write Fault, and Hour Meter.
All FDD components are mounted on a base assembly. The front panel has a spring
loaded door through which the'diskette is installed. The door is mechanically linked
to the disk loading mechanism and the head load interlock switch; therefore, when the
door is closed the Read/Write head may be loaded on the diskette in preparation for the
transfer of data.
Standard Models Versus Daisy-Chain Models - Throughout this manual certain features
and operation of the Flexible Disk Drive are described in terms of the manner in which
the FDD is designed to be connected to its controller, either standard or daisy chain.
Standard models are designed to be connected to their associated controller in star
fashion wherein each FDD unit has its own complete umbilical cable connection to the
controller, with no interconnection between FDD units. Standard FDD model units
are always
in
a ready state for reading or writing operation after initial preparation
and turn on.
Daisy-chain models are designed so that one to four FDD units may be connected
seria.lly to a common contro.ller. The controller continously monitors the operational
readiness of each FDD in its chain and commands and controls the reading and writing
operation of any selected FDD unit in its chain.
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