Overview
ISO/IEC 1864:1992 defines the physical and magnetic characteristics of unrecorded 12.7 mm (0.5 in) wide magnetic tape on reel for digital information interchange. It covers three physical recording densities - 32 ftpmm (800 ftpi) and 356 ftpmm (9 042 ftpi) using NRZI, and 126 ftpmm (3 200 ftpi) using phase encoding - and establishes test methods, environmental conditions, and interchange requirements to ensure magnetic and mechanical compatibility between information processing systems.
Key topics and requirements
- Tape construction
- Base material: oriented polyethylene terephthalate (PET) film or equivalent.
- Total thickness: 0.048 mm ± 0.008 mm; base thickness nominal 0.038 mm.
- Coating thickness: ≤ 0.015 mm; magnetic coating on one side.
- Dimensions and winding
- Width: 12.7 mm ± 0.0004 in.
- Normal minimum length: 732 m (2 400 ft) splice-free (shorter lengths must be stated).
- Wind with magnetic surface toward reel hub, clockwise when viewed from front; winding tension 2 N to 3.6 N.
- E value (flange overhang): minimum 3.2 mm; special range for self-loading cartridges.
- Recording densities & encoding
- Supported physical recording densities: 32, 126, 356 ftpmm (800, 3 200, 9 042 ftpi).
- Encoding: NRZI at 32 and 356 ftpmm; Phase encoding at 126 ftpmm.
- Magnetic reference & calibration
- Defines Standard Reference Amplitude (SRA), Reference Field and Standard Reference Current.
- Master and Secondary Standard Reference Tapes (NIST SRM 3200 and SRM 6250) for traceability.
- Performance & tests
- Typical field tolerances per density (+20% at 32 ftpmm, +15% at 126 ftpmm, +10% at 356 ftpmm).
- Average Signal Amplitude readback tolerances relative to SRA.
- Missing/extra pulse tests, ease-of-erasure after DC erasure, and signal uniformity.
- Mechanical properties: elastoplastic elongation limits, longitudinal curvature (minimum radius), and tape wind behavior.
- Markers, reflectivity & electrical properties
- BOT and EOT reflective markers positioning, size and reflectivity (marker ≥ 90% of aluminium reference).
- Tape backing reflectivity ≤ 30% of reference; magnetic surface resistance range 5×10^5 Ω to 5×10^8 Ω.
Applications and users
- Manufacturers of magnetic tape media and self-loading cartridges.
- Tape drive and legacy data-storage equipment designers and integrators.
- Test labs and QA teams validating tape supply for archival, backup and interchange.
- Organizations preserving interoperability of legacy tape formats that use 12.7 mm (0.5 in) magnetic tape, NRZI and phase-encoded recordings.
Related standards
Keywords: ISO/IEC 1864:1992, magnetic tape, 12.7 mm, NRZI, phase encoded, 32 ftpmm, 126 ftpmm, 356 ftpmm, tape interchange, SRA, NIST.