Overview
ISO 6586:1980 specifies how to implement the ISO 7‑bit and 8‑bit coded character sets on punched cards. It defines the representation of 7‑bit and 8‑bit binary combinations on 12‑row (12‑line) punched cards, derived from and compatible with the traditional Hollerith code. The standard is intended to ensure wide compatibility with existing punched‑card files and to support general interchange of information among data‑processing systems that use 12‑row cards.
Key topics and requirements
- Mapping of bit combinations to punch positions: The standard provides a fixed mapping from each of the 256 possible 8‑bit combinations to specific hole arrangements across the 12 positions of a card column. Positions are numbered 12, 11, 0, 1, 2, …, 9.
- 8‑bit implementation rules: The arrangement rules yield 256 distinct perforation patterns (noted as 32 × 8 in the standard), with the full 8‑bit grid covered in the second half of the specification (columns 00–07 in the table).
- 7‑bit implementation rules: The first half of the table (columns 00–07) corresponds to the 128 combinations of a 7‑bit set by ignoring the most significant bit (bit 8 or b7).
- Tabular and graphical material: ISO 6586 includes a main table (Table 1) mapping binary combinations to column/line positions and an auxiliary table (Table 2) providing an alternate presentation of the 256 arrangements; a figure shows the 12 possible punch positions in a column.
- Scope limits: The standard deals only with logical representation on 12‑row cards. It does not define the number of columns per card, hole shape, card material, nor error‑detection or redundancy techniques.
Applications and typical users
- Legacy data interchange: Organizations exchanging data stored on 12‑row punched‑card media benefit from a consistent encoding compatible with existing Hollerith‑based files.
- Data migration and archival: Archivists and IT teams converting punched‑card archives into modern formats can use the ISO 6586 mapping to decode legacy character data reliably.
- Hardware and emulator developers: Manufacturers of card punches/readers, emulation software authors, and system integrators implementing or testing punched‑card I/O can apply the specified mappings.
- Standards and interoperability teams: Those responsible for maintaining interoperability between historical and contemporary data‑processing environments.
Related standards
- ISO 646 (7‑bit coded character set)
- ISO 2022 (code extension techniques - related evolution of character handling)
- ISO 4873 (8‑bit coded character set for information interchange)
- ISO 1681 / ISO 1682 (blank card and physical punched‑card specifications)
Keywords: ISO 6586, punched cards, ISO 7‑bit, ISO 8‑bit, Hollerith Code, 12‑row punched cards, character encoding, legacy data interchange, punched card files.
Open preview (PDF)Data processing — Implementation of the ISO 7- bit and 8- bit coded character sets on punched cards