Overview
ISO/IEC 14776-381:2000 - Information technology - Small Computer System Interface (SCSI) - Part 381: Optical Memory Card Device Commands (OMC) - defines the SCSI command-set extensions and device model required to operate optical memory card devices. It is intended to be used together with the SCSI-3 Primary Commands (SPC) and SCSI-3 Block Commands (SBC) clauses to form the complete command set for OMC-class devices.
Key points:
- Targets removable optical memory card devices (INQUIRY peripheral device type = 0Fh).
- Media is write-once, non-volatile and preformatted (see ISO/IEC 11694-4).
- Defines device behaviour, addressing modes, command set extensions and parameters unique to optical memory cards.
Key topics and technical requirements
- Device model and identification
- Optical memory card devices return 0Fh in INQUIRY responses and support ID‑1 card size media.
- Addressing modes
- Two address types controlled by the AT bit in the mode parameter header:
- AT = 0: partition number + logical block address (LBA in partition)
- AT = 1: type of sector + track address + sector address
- AT is selected by MODE SELECT and reported by MODE SENSE.
- Sector and capacity
- Uses variable‑size sectors to optimize storage; sector type is defined per ISO/IEC 11694-4.
- Defines the READ CARD CAPACITY command (opcode 25h) - similar to READ CAPACITY but interpreted per the current address type and partition/track semantics.
- Command set
- Provides mandatory and optional commands for OMC devices (examples: INQUIRY, READ(10), WRITE(10), WRITE AND VERIFY, SEEK(10), READ CARD CAPACITY, REQUEST SENSE, MODE SENSE, MODE SELECT).
- Error reporting and sense keys
- Lists expected CHECK CONDITION triggers and associated sense keys (e.g., ILLEGAL REQUEST for invalid address, MEDIUM ERROR for unrecovered read errors, BLANK CHECK for reads of unwritten blocks, DATA PROTECT for write protection).
- Parameters
- Defines diagnostic, log and mode parameters specific to optical memory card devices.
Applications and who uses it
- Device manufacturers (optical memory card drives and media) for firmware and hardware compliance.
- Embedded/firmware developers implementing SCSI device behaviour for OMC devices.
- System integrators, OS storage stack and driver developers supporting optical memory card peripherals.
- Test laboratories and certification bodies verifying conformance with SCSI OMC behaviour.
Related standards
This standard is essential for anyone implementing or integrating SCSI-based optical memory card devices and ensures interoperable behaviour for addressing, command handling (including READ CARD CAPACITY), error reporting and device-specific parameters.
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