SCSI Commands - USB Mass Storage: Designing and Programming Devices and Embedded Hosts - page 132

The INCITS Technical Committee T10 ( www.t10.org) has these specifica-
tions:
SCSI Architectural Model (SAM). Defines a reference model that applies to
all SCSI devices. The current version is SAM-3.
SCSI Primary Commands (SPC). Defines commands that apply to all SCSI
devices. The current version is SPC-3.
SCSI Block Commands (SBC). Defines commands used by hard drives,
flash drives, and other direct-access block devices. The current version is
SBC-3.
Multi-Media Commands (MMC). Defines commands used by CD and
DVD drives. The current version is MMC-4.
INCITS Technical Committee T13 ( www.t13.org) has this specification:
ATA/ATAPI . Defines commands used by CD and DVD drives. The cur-
rent version is ATA/ATAPI - 7.
The SFF Committee ( www.sffcommittee.com ) has these specifications:
ATA Packet Interface for CD-ROMs (SFF-8020i). An earlier version of the
ATA/ATAPI specification.
ATAPI Removable Rewritable Media Devices (SFF-8070i). Commands that
apply to some floppy drives.
Working drafts of the documents from INCITS are available from
www.t10.org and www.t13.org. Approved standards are ANSI documents
sold by Global Engineering Documents ( www.global.ihs.com) .
Rather than repeating every detail about the command blocks from the
specifications, this chapter is more of a companion guide to the specification
documents. The guide explains the purpose and use of common commands
and provides application hints for implementing the commands in device
firmware.
Which Commands to Implement?
A question many firmware programmers have is which SCSI commands a
device must implement. Each device specifies a command set in the
response to a SCSI INQUIRY command, and the command set's specifica-
tion lists mandatory commands. For example, a device that returns an