ISO/IEC 8441-2:1991

ISOAEC
INTERNATIONAL
STANDARD
First edition
1991-08-01
Information technology - High density digital
recording (HDDR) -
Part 2:
Guide for interchange practice
Technologies de I ’informa fion --- Enregistrement nun&-ique Zl harrte
densife (HDUR) -
Partie 2: Guide pour I ’echange d ’informafion
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--- -_.__ .---
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Reference number
ISOAEC 8441=2:1991(E)
Contents
Page
1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v. . 1
2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
...................... 1
3 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
4 Recording and reproducing characteristics . . .
. . . . . . . . . . . . . . . . . . . . . . . . .*. 4
General
4.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ._. 4
4.2 Tape Speeds
. . . . . . . . . . . .I. 4
4.3 Track configurations . .
.................... 5
4.4 RecordeVreproducer characteristics .
. . 5
4.5 Other characteristics . 6
....................
5 Methods for high density digital recording . . 15
5.1 Introduction ._._.,. 15
5.2 Record transfer function . .
............. 15
5.3 Flux transition densities and rates for high density recording 15
5.4 Data input/output .-.-.-.-.-. 16
5.5 Data sense . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-. 16
5.6 Reproduce equalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . .~.
5.7 Other System Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
0 ISO/IEC 1991
All rights reserved. No part of this publication may be reproduced or utilized in any form
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Permission in writing from the publisher.
ISO/IEC Copyright Office l Case Postale 56 l CH-1211 Genhve 20 l Switzerland
Printed in Switzerland
ii
ISO/IEC 84452:1991 (E)
5.8 Auxiliary data recording . . . . . . . . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . ._._. 17
Annexes
A Operating modes, Performance categories, and Cross-play criteria
for high density PCM recordinq Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
.
A.l Performance categories . . 18
AI1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
A.1.2 Record head gap length for category A and category B
Performance . . . . . . . . . . . . . ._.-.-.-.-. 18
A.1.3 Record head gap lenqth for category C Performance . . . . . . . . 18
\
A.1.4 Operating modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
A.2 Single track serial high density recording . 19
A.2.1 Serial high density recording with wideband analogue
recorder/reproducer (category A) . 19
.................................. 21
A.2.2 Parallel high density digital recording
B Recording techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ._. 22
B.l Recording code names and their abbreviations . 22
8.2 Enhanced NRZ format for parallel HDDR . 22
B.2.1 ENRZ coding .
B.2.2 ENRZ - parallel HDDR format . 22
...................................... 22
B.2.3 Summary of enhanced NRZ format
B.3 Miller squared format (M*) for parallel HDDR . . . . . . . . . . . . . . . . . . . . . . . 23
B.3.1 Miller squared coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B.3.2 M* format for parallel HDDR . . . . 23
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
B.3.3 Summary of M* formst
B.3.4 M* format bandwidth utilization/packing density . 24
B.4 Randomized NRZ-L format parallel HDDR . 24
8.4.1 RNRZ-L coding . . 24
B.4.2 RNRZ-L parallel HDDR format . . . ._._. 24
8.4.3 Summary of randomized NRZ-L format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
B.4.4 Randomized NRZ-L format bandwidth utilization/packing
density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8.5 PROP format for parallel HDDR (Pseudo random odd parity) 26
B.5.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*.m.
. . .
Ill
B.5.2 Summary of PROP format .
....................................... 27
8.5.3 PROP format bandwidth utilization
B.6 3PM formats for parallel HDDR . 27
B.6.1 General .
8.6.2 3PM format Versions .
Error detection and correction (formats A and B) . 29
B.6.3
....................................... 29
8.6.4 Summaty of 3PM formats A and B
3PM format bandwidth utilization . 30
B.6.5
B.7 MODAS airborne recording format . 30
B.7.1 General . . . ‘.- . 30
B.7.2 Description . . . 30

ISOAEC 8441-2:1991 (E)
Foreword
ISO (the International Organization for Standardization) and IEC (the
International Electrotechnical Commission) form the specialized systern
for worldwide standardization. National bodies that are members of ISO
or IEC participate in the development of International Standards th ‘rough
technical committees established by the respective organization to deal
with particular fields of technical activity. ISO and IEC technical com-
mittees collaborate in fields of mutual interest. Other international or-
ganizations, governmenfal and non-governmental, in liaison with ISO
and IEC, also take patt in the work.
In the field of information technology, ISO and IEC have established a
joint technical committee, ISO/IEC JTC 1. Draft International Standards
adopted by the joint technical committee are circulated to national bod-
ies for voting. Publication as an International Standard requires ap-
proval by at least 75 % of the national bodies casting a vote.
International Standard ISO/IEC 8441-2 was prepared by Joint Technical
Committee ISO/IEC JTC 1, Information technology.
ISO/IEC 8441 consists of the following Parts, under the general title In-
formation technology - High density digital recording (HDDR):
- Part 1: Unrecorded magnetic tape for (MUX?) applications
- Part 2: Guide for interchanqe practice
L
Annexes A and B of this par-t of ISO/IEC 8441 are for information only.

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INTERNATIONAL STANDARD ISO/IEC 844%2:199l(E)
Information technology - High density digital recording
(HDDR) -
Part 2:
Guide for interchange practice
ISO/IEC TR 6371:1989, Information processing --
1 Scope
Interchange practices and test methods for unre-
corded instrcrmentation magnetic tape-
This part of ISO/IEC 8441 specifies the minimum
Performance levels necessary for the effective
interchange of information using High Density Digital
Recording (HDDR). lt also describes methods of
3 Definitions
testing for determining these levels. lt gives guid-
ante on recorders/reproducer characteristics,
For the purposes of this part of ISO/IEC 8441, the
modes of recording, and modulation Patterns.
following definitions apply.
The imperial dimensions given in this part of
ISO/IEC 8441 are the reference dimensions. The
3.1 aliasing: The false lower frequency components
metric and imperial dimensions are, however, given
resulting from an insufficient satnpling rate (i.e. less
to a sufficient degree of accuracy as to be totally
than required by the sampling theorem) when re-
interchangeable.
constructing an analogue Signal from its sampled
data representation.
3.2 baseline restorer: A device to restore the d.c.
2 Normative references -
component removed by the record/reproduce pro-
cess.
The following Standards contain provisions which,
through reference in this text, constitute provisions
3.3 bit error: The incorrect interpretation of a bi-
of this part of ISO/IEC 8441. At the time of publica-
nary bit by a message processing unit.
tion, the editions indicated were valid. All Standards
are subject to revision, and Parties to agreements
3.4 bit error rate (BER): The rate at which bit errors
based on this part of ISO/IEC 8441 are encouraged
occur in a message processing unit, expressed in
to investigate the possibility of applying the most
terms of the number of bit errors divided by the total
recent editions of the Standards indicated below.
number of bits processed in a given period of time,
Members of IEC and ISO maintain registers of cur-
or from a given length of tape.
rently valid International Standards.
3.5 bit packing density: The number of bits re-
ISO/IEC 3788: 1990, Information processing - 9-track,
corded per unit track length, usually expressed in
12,7 mm (0,5 in) wide magnetic tape for information
terms of bits per millimetre (bit/mm) or kilobits per
inferchange using Phase encoding at 126 ftpmm (3
inch (kbit/in).
200 ftpi), 63 cpmm (1 600 cpi).
ISO 6068: 1985, Information processing -- Recording 3.6 bit Slip: The condition in a message processing
characteristics of instrumentation magnetic tape (in- unit where the bit rate clock has gained (or lost)
cluding felemefry Systems) -- Interchange require- more than 180° phasing with respect to synchronism
ments. with the binary message bits.

ISOAEC 8441-2:1991(E)
NOTE 5
When recording, this is equal to the head
3.7 bit synchronizer: An information processing
spacing, but on reproducing it is equal to head spacing
unit intended to extract the binary message and as-
only when the record and reproduce tensions and head
sociated bit rate clock included in a pulse code
spacing are equal.
modulation (PCM) Signal.
3.15 decoder: Information recovery device that ac-
3.8 Cross play: The ability to record and reproduce
cepts digital Signals from the tape reproducer and
on the Same or a different machine, or record at one
converts them into a form suitable for the output
Speed and reproduce at the Same or different Speed.
interface.
3.9
Cross talk: Interference Signals that are coupled
3.16 digital recording Code: The on-tape digital
from adjacent channels into a given processing unit
coding of the recorded binary message.
channel, usually expressed in terms of decibels
down from full scale amplitude of the unit channel.
3.17 dropout: Reduction in the reproduce Signal
amplitude severe enough to Cause bit errors.
3.10 data azimuth: The instantaneous angle in the
plane of the tape between a line perpendicular to
3.18 duty factor (of a pulse): The ratio of pulse du-
the reference edge and either of the two parallel
ration to pulse period, often expressed as a per-
lines defining data scatter.
centage.
NOTE 1 Data azimuth may be expressed as the sum of
static and dynamic components in the form 3.19 edge margin (AY): The distance between the
outside edge of the highest numbered track and the
A + nf(t)
tape edge (see figure3).
t
3.20 edge margin, minimum (d&,,): The minimum
&)dt = 0
value of the edge margin.
s
NOTE 6 This value places an additional constraint on
3.11 data azimuth (dynamic): The maximum angu- track configurations since, in general, the simultaneous
lar deviation, over a period of time, of the data application of all worst-case tolerantes for track width,
track location, and tape width will result in a value of edge
azimuth from its mean value as defined by data
margin less than M,.
azimuth (static). For the purpose of this definition,
the word “maximum” is interpreted as being at the
95 % probability level. For a Gaussian distribution, 3.21 encoder: A processing device that accepts a
this is two Standard deviations (20). data stream at its input and converts it to appropri-
ate digital Signals to be recorded on tape.
NOTE 2 Data azimuth (dynamic) is the maximum value
of the quantity R/(t) in 3.10.
3.22 error detection: The process of detecting bit
errors.
3.12 data azimuth (static): The mean value, over a
period of tirne, of the data azimuth.
3.23 error correction: The process of correcting
detected bit errors.
NOTE 3 Data azimuth (static) is the quantity R in 3.10.
3.24 eye Pattern: The Pattern as displayed on an
3.13 data scatter: The minimum distance between
oscilloscope, that results from the superpositioning
two parallel lines, in the plane of the tape, enclosing
of the wavef
...