Domain validation
Encyclopedia
Domain Validation is part of the SCSI
standard. It describes how to negotiate the best possible transfer agreement between two devices. There are three different messages that can be sent:
WDTR is used only to negotiate width (8 or 16 bit).
SDTR can be used to negotiate up to Ultra-2 speeds.
PPR subsumes the capabilities of both WDTR and SDTR and can negotiate speeds of up to Ultra-640. It can also set various parameters, such as Information Units, Quick Arbitration Select and Double Transition clocking.
SCSI
Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it...
standard. It describes how to negotiate the best possible transfer agreement between two devices. There are three different messages that can be sent:
- SDTR (Synchronous Data Transfer Request)
- WDTR (Wide Data Transfer Request)
- PPR (Parallel Protocol Request)
WDTR is used only to negotiate width (8 or 16 bit).
SDTR can be used to negotiate up to Ultra-2 speeds.
PPR subsumes the capabilities of both WDTR and SDTR and can negotiate speeds of up to Ultra-640. It can also set various parameters, such as Information Units, Quick Arbitration Select and Double Transition clocking.