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Inside Macintosh: Operating System Utilities /
Chapter 9 - Start Manager / Start Manager Reference
Routines / Identifying and Setting the Default Startup Device


SetDefaultStartup

You can use the SetDefaultStartup procedure to write information to parameter RAM that specifies the default startup device.

PROCEDURE SetDefaultStartup (paramBlock: DefStartPtr);
paramBlock
A pointer to a default startup device parameter block.
for a slot device
-->sdExtDevIDSignedByteExternal device ID.
-->sdPartitionSignedByteReserved.
-->sdSlotNumSignedBytePhysical slot number.
-->sdSRsrcIDSignedByteSlot resource ID (SResourceID).

for a SCSI device
-->sdReserved1SignedByteReserved.
-->sdReserved2SignedByteReserved.
-->sdRefNumIntegerDriver reference number.

DESCRIPTION
The SetDefaultStartup procedure writes information to parameter RAM that specifies the default startup device. The default startup parameter block of data type DefStartType defines two kinds of startup devices: either a slot or a SCSI device. To specify a slot device as the default, pass the external device ID, the slot number, and the slot resource ID. The external device ID, supplied by the slot's driver, identifies a particular device connected through that slot. It's possible that the card in this slot could have several devices connected to it.

To specify a SCSI device as the default, pass its driver reference number (always negative) in the sdRefNum field. To specify no device as the default, pass a value of 0 in this field.

ASSEMBLY LANGUAGE INFORMATION
The registers on entry and exit for this routine are
Registers on entry
A0Address of the default startup device parameter block
Registers on exit
A0Address of the default startup device parameter block

SEE ALSO
For more information about the default startup device parameter block see "The Default Startup Device Parameter Block" beginning on page 9-18.

To retrieve information about the default startup device, see the description of the GetDefaultStartup procedure described on page 9-20.


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6 JUL 1996

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