Inside Macintosh: Devices /

Chapter 3 - SCSI Manager / SCSI Manager Reference

SCSI Manager Routines /

SCSISelAtn

You can use the SCSISelAtn function to select a SCSI device and at the same time to assert the attention (/ATN) bus signal.

FUNCTION SCSISelAtn (targetID: Integer): OSErr;

targetID

The SCSI ID of the target device, with a value from 0 to 6.

DESCRIPTION

The SCSISelAtn function is identical to the SCSISelect function except that this function asserts the /ATN signal during selection. The /ATN signal informs the target that the initiator wants to send a message. The SCSISelAtn function must be followed by a call to the SCSIMsgOut function to send the message to the target device.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for SCSISelAtn are

Trap macro	Selector
_SCSIDispatch	$000B

RESULT CODES

noErr	0	No error
scCommErr	2	Communications error, operation timeout

SEE ALSO

See "SCSI Bus Signals," beginning on page 3-4, and "SCSI Bus Phases," beginning on page 3-5, for more information about the attention signal and the selection phase.