【国外标准】 Information technology - SCSI Multi-Media Commands - 2 (MMC-2)

This standard defines a multimedia command set extensions for Device Type 5 devices. The commands specified within this standard define standard access and control to those Features of the device that are used in multimedia applications. The SPC command set and these extensions are transport independent and may be implemented across a wide variety of environments for that a SCSI command mapping and delivery vehicle has been defined. To date these include Fibre Channel, SCSI Parallel Interface, High Performance Serial Bus, Serial Storage Architecture, and ATA/ATAPI. The objective of this command set is to provide for the following: 1) A definition of the command formats and functions independent of delivery, protocol/signaling or transport mechanism. Architectural constraints regarding command functions, over the various transports, are addressed in the document specific to the physical transport. 2) Standardized access to common Features of SCSI devices employed in multimedia applications. 3) System software/firmware independence across device classes. Thus, different tape drives, optical media drives, and other devices can be added to the system without requiring modifications to generic system hardware and software. Provision is made for the addition of special Features and functions through the use of vendor-specific options. Reserved Opcodes are provided for future standardization. 4) To provide compatibility such that properly conforming SCSI-2 devices may inter-operate with subsequent devices given that the system engineering is correctly done. SCSI protocol extensions are designed to be permissive of rejections by conforming SCSI-2 devices and thus allow the SCSI-2 device to continue operation without requiring the use of the extension.