Overview
ISO 962:1974 is an international standard published by the International Organization for Standardization (ISO) that specifies the implementation of the 7-bit coded character set, along with its 7-bit and 8-bit extensions, on 9-track magnetic tape systems. The magnetic tape referenced is 12.7 mm (0.5 inch) wide and includes 9 parallel tracks used to record digital information.
This standard addresses the physical and logical representation of alphanumeric data on magnetic tape media, ensuring compatible data exchange between different information processing systems and devices. Originally approved in 1974, ISO 962 aligns with ISO 646 for 7-bit character coding and extends its use specifically for magnetic tape recordings, including error detection and data block formatting.
Keywords: ISO 962, 7-bit coded character set, 9-track magnetic tape, 12.7 mm tape, information processing, character encoding, data storage, magnetic tape standard.
Key Topics
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7-bit and 8-bit Character Encoding Extensions
ISO 962 specifies how to encode characters using a 7-bit code along with 7-bit and 8-bit extensions to support a broader range of symbols and control characters on magnetic tape.
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9-Track Magnetic Tape Structure
The standard details the physical layout of magnetic tape, including the numbering and arrangement of the nine tracks (with track 1 adjacent to a defined reference edge) and how bits are recorded in rows across these tracks.
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Data Block Composition
Data on the tape is organized into blocks ranging from a minimum of 18 rows to a maximum of 2,048 rows. Each row represents one character plus a parity bit, with additional rows added for error control and block delimitation.
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Error Detection Methods
ISO 962 mandates a parity scheme where the parity bit is stored on track 4, ensuring an odd number of ‘1’ bits per row, and a longitudinal redundancy check at the end of each block to verify the overall integrity of the recorded data.
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Data Formatting and Control
The standard covers control blocks ("marks on tape") used to separate data blocks, ensuring reliable data interpretation and transitions during reading and writing processes.
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Data Recording Direction and Reference
The tape orientation, labeled edges, and recording directions are specified to maintain uniformity in recording and playback across devices.
Applications
ISO 962:1974 is essential for:
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Magnetic Tape Data Storage Systems
Used by organizations and industries reliant on large-scale data archival or transfer, where magnetic tapes serve as a durable medium for storing textual and coded information.
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Legacy Systems and Data Migration
Facilitates compatibility when interfacing older computer systems or data archives with modern equipment, enabling standardized reading and writing of character data on magnetic tapes.
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Interoperability in Information Processing
Allows seamless exchange of coded textual information between devices from different manufacturers or countries by defining a universal encoding scheme and physical tape format.
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Error-Resistant Data Transmission
Ensures data integrity through parity and redundancy checks, making it suitable for mission-critical applications where error detection during storage and retrieval is vital.
Related Standards
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ISO 646 – Defines the original 7-bit coded character set used for information interchange, foundational for the character encoding specified in ISO 962.
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ISO 2022 – Specifies techniques for extending 7-bit coded character sets, important for understanding the 7-bit and 8-bit extensions utilized on the tape.
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ISO/R 1862, ISO/R 1863, ISO 1864 – Outline specifications for 9-track magnetic tapes with various recording densities and encoding methods, complementing the physical media requirements of ISO 962.
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ISO/R 1001 – Covers labeling and file structure on magnetic tapes, relevant for the control blocks and data organization mentioned in the standard.
ISO 962:1974 remains a valuable reference for organizations managing data storage on magnetic tape media, dictating precise guidelines for 7-bit coded character representation and ensuring interoperability, reliability, and data integrity across compatible systems.
Open preview (PDF)Information processing — Implementation of the 7- bit coded character set and its 7- bit and 8-bit extensions on 9- track 12,7 mm (0.5 in) magnetic tape