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UDC 681.3.042 : 003.62 : 62-05
IS0
INTERN AT1 ON A L O RG A N IZATl O N FOR STAND AR Dl2 ATlON
IS0 RECOMMENDATION
R 840
CODE FOR NUMERICAL CONTROL OF MACHINES
(Compatible with the IS0 7 bit character set)
1st EDITION
October 1968
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country. being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 840, Code for numerical control of machines (Compatible with
tlic IS0 7 bit character set), was drawn up by Technical Committee ISO/TC 97, Computers and
inforination processing, the Secretariat of which is held by the United States of America Standards
Institute (USASI).
Work on this question by the Technical Committee began in 1963 and led, in 1967, to the
adoption of a Draft IS0 Recommendation.
In August 1967. this Draft IS0 Recommendation (No. 1314) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature,
by the following Member Bodies :
Belgium Japan Switzerland
Czechoslovakia Netherlands Turkey
Denmark New Zealand U.A.R.
France Poland United Kingdom
Germany Portugal U.S.A.
Iran Spain
Italy Sweden
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council,
which decided, in October 1968, to accept it as an IS0 RECOMMENDATION.
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ISO/R 840-1968 (I
IS0 Recommendation R 840 Octo ber 1968
CODE FOR NUMER CAL CONTROL OF MACH
(Compatible with the IS0 7 bit character set)
1. SCOPE
This IS0 Recommendation describes a 7 bit coded character set for the numerical control of machines
and associated equipment (printers, punchers); it is to be implemented on 8-track punched tape.
This IS0 Recommendation consists of a table, notes and a key. An Annex gives the meanings assigned
to the symbols in the IS0 Recommendations on punched tape block formats.
2. REFERENCES
2.1 The recommended character set is based upon and compatible with the IS0 7 bit coded
character set, described in IS0 Recommendation R 646, 6 and 7 bit coded character sets for
information processing interchange.
2.2 The implementation of this coded character set on punched tapes is in accordance with IS0
Recommendation R .,* Representation of 6 and 7 bit coded character sets on punched tape;
it includes a parity check (even parity); the parity bit is on track 8.
2.3 The techni
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