Tiêu chuẩn quốc tế

• Số hiệu / Standard Number: ANSI/INCITS 54:1986
• Năm ban hành / Publication date: 1986
• Tình trạng / Status: A - Còn hiệu lực
• Tên tiếng Anh / Title in English: Information Systems – Recorded Magnetic Tape for Information Interchange – (6250 CPI, Group-Coded Recording)
• Số trang / Page: 22

Phạm vi áp dụng / Scope of standard

Scope and Purpose

This standard provides specifications for a l/2-inch (12,7-mm), g-track magnetic tape to be used for information interchange among information processing systems, communication systems, and associated equipment utilizing a standard code as agreed upon by the interchange parties. This standard deals solely with recording on magnetic tape and supports and complements American National Standard for Unrecorded Magnetic Tape for Information Interchange (g-Track 800 CPI, NRZI; 1600 CPI, PE; and 6250 CPI, GCR), ANSI X3.40-1 983, where the following are dealt with in detail: general requirements, definitions, tape physical and magnetic requirements, and tape reel requirements. Compliance with the standard for unrecorded tape is a requirement for information interchange. The use of a labeling standard such as American National Standard Magnetic Tape Labels and File Structure for Information Interchange, ANSI X3.27-1978 will support data interchange between data processing systems.

CAUTION NOTICE: The user's attention is called to the possibility that compliance with this standard may require use of an invention covered by patent rights.

By publication of this standard, no position is taken with respect to the validity of this claim or of any patent rights in connection therewith. The patent holder has, however, filed a statement of willingness to grant a license under these rights on reasonable and nondiscriminatory terms and conditions to applicants desiring to obtain such a license. Details may be obtained from the publisher.

No representation or warranty is made or implied that this is the only license that may be required to avoid infringement in the use of this standard.

This standard defines the requirements and supporting test methods necessary to ensure interchange at acceptable performance levels. It is distinct from a specification in that it delineates a minimum number of restrictions consistent with compatibility in interchange transactions.

The performance levels contained in this standard represent the minimum acceptable levels of performance for interchange purposes. They, therefore, represent the performance levels which the interchanged items should meet or surpass during their useful life and thus define end-of-life criteria for interchange purposes. The performance levels in this standard are not intended to be employed as substitutes for purchase specifications.

Wherever feasible, quantitative performance levels that must be met or exceeded in order to comply with this standard are given. In all cases, including those in which quantitative limits for requirements falling within the scope of this standard are not stated but left to agreement between interchange parties, standard test method and measurement procedures shall be used to determine such limits.

U.S. engineering units are the original dimensions in this standard. Conversions of toleranced dimensions from customary U.S. engineering units (similar to British Imperial Units) to SI units have been incorporated in this standard according to Method A as described in American National Standard Metric Practice, ANSI/ IEEE 268-1982, and in International Standard for Toleranced Dimensions - Conversion from Inches into Millimetres and Vice Versa, IS0 370-1975. Method A should be used to achieve economy unless a requirement for absolute assurance of fit justifies use of Method B. In the national standards of IS0 member bodies, additional rounding may be done to produce "preferred " values. These values should lie within or close to the original tolerance.

Except as indicated in 1.4, interchange parties complying with the applicable standards should be able to achieve compatibility without need for additional exchange of technical information.