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Data General Corporation (DCCI hu prepared this manual for use by DCC personnel and customers as a guide to the proper
in~tallation:
open1tion', and.
main~enance
of DCC
equi~me~t
and
software. The drawings and specifications contained herein are the property of DCC and shall neither be reproduced in whole or m part without DGC s prior written approval nor be implied to
grant any license to make, use, or sell equipment manufactured in accordance herewith.
CHAPTER I
OVERVIEW
THIS MACHINE, AN INTRODUCTION
Data General's 6020 series transports are reliable,
75ips, vacuum column tape drives, available for half
inch magnetic tape in 7-track and 9-track format.
Data is recorded in IBM-compatible NRZI format at
800 and 556bpi, and the tapes produced are widely
interchangeable with other industry standard tape
units.
Magnetic tape transports move magnetic tape past a
transcription head where data is written and read in
nine parallel tracks across the half inch tape width.
Format requirements necessitate that the tape can be
brought from a stop to full speed (75ips) before 1/4"
passes the transcription head, and that the tape speed
be accurate within 5%. The fragility of magnetic tape
requires that gentle tension of about 8oz be steadily
maintained on the tape while it is moving - and when
it is accelerating or decelerating.
A system diagram of the transport is shown on the
next page. The transport contains four principal
systems which work independently . to provide
reliable, gentle tape handling. They are:
• The operators panel and control logic
• The data handling circuits
• The capstan and its servo system
• The vacuum column servo systems.
Operators Panel and Control Logic
The operators panel and its associated control logic·
direct the local operation of the transport and link it
to the computer's tape subsystem when the unit is on
line. The operators panel contains switches for
powering up the transport, loading the vacuum
columns, and assigning the unit's identity in a tape
subsystem. The control logic provides system status
information to the computer when the unit is on line.
Data Handling Circuits
Data is transcribed to tape along a 9-bit wide data
path. Static deskew adjustments in each channel
ensure that data characters are written in a straight
line perpendicular to the length of the tape. A 9-bit
wide path moves the data read from tape to the
subsystem controller. A bank of amplifiers and peak
detectors convert low amplitude analog pulses from
the read head to TTL-level signals compatible with
the controller. The data reading path also includes
certain timing logic to properly synchronize data
transfers. Since reading and writing are done
independently of each other at the transcription head,
data can be verified almost immediately as it is
written without reversing the tape to reread a section.
1-1 of6
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