Overview
ISO 7665:1983 - "Information processing - File structure and labelling of flexible disk cartridges for information interchange" defines a standardized way to record labels, blocks and file structures on flexible disk cartridges so information can be exchanged between different information‑processing systems. The standard specifies label formats (Volume, File and Error Map labels), basic block and record characteristics, the organization of disk space (index cylinder, cylinders, tracks, sectors), and three nested levels of interchange: BASIC INTERCHANGE (BI), EXTENDED INTERCHANGE LEVEL 1 (EI) and EXTENDED INTERCHANGE LEVEL 2 (E2).
Key topics and requirements
- Labeling conventions: Standardized fields and character coding for the Volume Label (VOL1), File Label (HDR1) and Error Map Label (ERMAP) to identify volumes, files, file sections and defective areas.
- Index cylinder (cylinder 00): Reserved for descriptive information. On side 0, physical records on cylinder 00 use a length of 128 data characters; specific sectors on Track 00 are allocated for system use, ERMAP, VOL1 and HDR1 entries.
- Blocks, records and files: Definitions and permitted structures for blocks, physical records, fixed‑length, variable‑length, and segmented records; extents (continuous physical-record sequences) and file sectioning across volumes.
- Disk organization parameters: Use of parameters such as Cylinder‑Limit, Index‑Sector‑Limit, Data‑Sector‑Limit, and Data‑Physical‑Record‑Length to define space layout and capacity per data interchange standard.
- Interchange levels:
- BI (Basic Interchange): Minimum facilities for interchange.
- EI (Extended Interchange Level 1): Adds blocked fixed‑length records and blocks longer than physical records.
- E2 (Extended Interchange Level 2): Adds variable‑length records and segmented records.
- Conformance: A cartridge conforms when all labels and interchange files meet ISO 7665 and the applicable flexible disk data interchange standard(s).
Applications - who uses it
- Legacy system integrators and data migration engineers preserving or exchanging data stored on 5.25" and 8" flexible disk cartridges.
- Data recovery specialists interpreting labels, ERMAP and file structures to recover lost data.
- Software developers implementing import/export tools for vintage formats.
- Hardware manufacturers of drives and controllers that claim compatibility with standardized interchange formats.
- Archives and museums maintaining long‑term access to floppy‑disk‑based records.
Related standards
Keywords: ISO 7665, flexible disk cartridges, file structure, labelling, data interchange, index cylinder, volume label, file label, ERMAP, interchange levels.