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Inside Macintosh: Devices /

Chapter 3 - SCSI Manager / SCSI Manager Reference

SCSI Manager Routines /

SCSICmd

You use the SCSICmd function to send a SCSI command to a SCSI device.

FUNCTION SCSICmd (buffer: Ptr; count: Integer): OSErr;

buffer

A pointer to a buffer containing the SCSI command descriptor block.

count

The size of the command descriptor block, in bytes.

DESCRIPTION

The SCSICmd function sends a SCSI command to the previously selected target device. The command code and other parameters are contained in a command descriptor block (CDB) data structure pointed to by the buffer parameter. The count parameter specifies the size of the CDB structure, which can be 6, 10, or 12 bytes.

The SCSI specification describes the CDB data structure and lists the standard SCSI commands that all devices must support. Devices may support additional commands not defined by the SCSI specification.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for SCSICmd are

Trap macro	Selector
_SCSIDispatch	$0003

RESULT CODES

noErr	0	No error
scCommErr	2	Communications error, operation timeout
scPhaseErr	X	Phase error on the SCSI bus

SEE ALSO

See "SCSI Commands," beginning on page 3-7, for an overview of SCSI commands. Refer to the SCSI specification for detailed information about SCSI commands.