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Inside Macintosh: Devices /

Chapter 3 - SCSI Manager / SCSI Manager Reference

SCSI Manager Routines /

SCSIGet

You use the SCSIGet function to arbitrate for control of the SCSI bus.

FUNCTION SCSIGet: OSErr;

DESCRIPTION

The SCSIGet function prepares the SCSI Manager to initiate the arbitration sequence. If the SCSI Manager is busy with another operation, this function returns the scMgrBusyErr result. If arbitration failed because the bus was busy, the function returns the scArbNBErr result.

IMPORTANT

The operation of the SCSIGet function varies on different Macintosh models and does not necessarily initiate the SCSI bus arbitration phase. In some Macintosh models, the arbitration phase does not occur until your program calls the SCSISelect function. However, your program must always call the SCSIGet function before calling SCSISelect.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for SCSIGet are

Trap macro	Selector
_SCSIDispatch	$0001

RESULT CODES

noErr	0	No error
scCommErr	2	Communications error, operation timeout
scArbNBErr	3	Bus busy, arbitration timeout
scMgrBusyErr	7	SCSI Manager busy

SEE ALSO

See "SCSI Bus Phases," beginning on page 3-5, for a description of the arbitration phase.