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Data interchange on 3,81 mm magnetic tape cassette (63 ftpmm, phase encoded at 32 bpmm)

3rd edition, September 1976

ECMA TC19 was set up by ECMA in January 1970 with aim to identifying and standardizing the physical properties and the relevant data format of a magnetic tape cassette for digital applications – below the performance range of existing magnetic tape standards – in order to ensure interchangeability.

It appeared to be a fact that the 3,81 mm tape cassette was already used and will be more used in computer applications.
The urgent need for a standard for this type of cassette was therefore recognized and-TC19’s first efforts were directed to setting up the present Standard ECMA-34, which was issued in September 1971.

This Standard was presented to ISO/TC 97 as a proposed draft for an international standard. Similar work was also in progress in the American National Standard Institute (ANSI). As a result ISO/TC97/SC11 eventually adopted a final draft for an international standard at their April 1973 meeting. The 2nd Edition of Standard ECMA-34 was in its content identical to this draft.

When it was finally edited at the July 1975 meeting of SC11, a few changes were introduced. The present 3rd Edition of ECMA-34 reflects these changes.

Essentially they concern two points:

  • magnetic properties can be checked on the same relative pass,
  • the integrity of gaps is defined as a number of flux transitions instead a length of tape.

Furthermore, a recommendation for the hub diameter has been introduced in this 3rd Edition to ensure exchangeability in case of reel- to-reel drives.

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SubcategoryNot Available

Technical CommitteeTC19 (this TC is no longer active)


  • ECMA-34, 1st editionNo file available
  • ECMA-34, 2nd edition, July 1973Download