Overview
ISO/IEC 14776-232:2001 - Information technology - Small computer system interface (SCSI) - Part 232: Serial Bus Protocol 2 (SBP-2) - defines the SBP-2 transport protocol for carrying SCSI commands, data and status over a High Performance Serial Bus. The standard specifies required behaviors, data structures and register models so that initiators and targets can exchange requests and responses reliably. Implementations must also conform to ISO/IEC 13213:1994 where indicated.
Key topics and requirements
- Transport protocol (SBP-2): Specifies how SCSI command, data and status are encapsulated and moved between nodes on a Serial Bus.
- Conformance: Implementations are required to follow this part of ISO/IEC 14776 plus referenced normative standards (notably ISO/IEC 13213:1994).
- Data structures: Detailed formats for Operation Request Blocks (ORBs) (command, management, dummy ORBs), page tables, and status blocks.
- Control and status registers: Core and serial-bus dependent CSR definitions and agent registers (e.g., ORB_POINTER, DOORBELL, AGENT_STATE).
- Configuration ROM: Layout and required directory entries (unit directories, command set IDs, Unit_Unique_ID, management agent, unit characteristics).
- Access and session management: Procedures for login, reconnect, logout, and access protocols between initiators and targets.
- Command execution and data transfer: Request lists, fetch agent behavior, data buffering (direct and indirect), completion status and unsolicited status handling.
- Task management: Task set model, task management requests (abort task, reset, etc.) and error conditions.
- Normative and informative annexes: Minimum node capabilities, SCSI encapsulation rules, security extensions, sample configuration ROMs and transaction error recovery.
Applications and who uses this standard
ISO/IEC 14776-232:2001 is primarily used by:
- Device manufacturers implementing SCSI-targets over a High Performance Serial Bus (firmware and hardware).
- Host adapter and controller vendors that build initiator implementations and drivers.
- Operating system and driver developers implementing SBP-2 device drivers and session management.
- System integrators and test labs validating interoperability, conformance testing and configuration ROM contents.
- Security and firmware engineers implementing the security extensions and management ORBs.
Practical uses include building interoperable storage devices, developing driver stacks for serial-bus attached SCSI devices, and defining device firmware behavior for login/reconnect and task management.
Related standards
- ISO/IEC 13213:1994 (referenced for conformance requirements)
- Other SCSI architecture and Small Computer System Interface standards for command set semantics and higher-level SCSI behavior.
Keywords: ISO/IEC 14776-232:2001, SBP-2, Serial Bus Protocol 2, SCSI over Serial Bus, Operation Request Block, configuration ROM, task management, control and status registers.
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