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


GetDefaultStartup

You can use the GetDefaultStartup procedure to return information about the default startup device.

PROCEDURE  GetDefaultStartup (paramBlock: DefStartPtr);
paramBlock
A pointer to a default startup device parameter block.
<--sdExtDevIDSignedByteExternal device ID.
<--sdPartitionSignedByteReserved.
<--sdSlotNumSignedBytePhysical slot number.
<--sdSRsrcIDSignedByteSlot resource ID (SResourceID).
<--sdReserved1SignedByteReserved.
<--sdReserved2SignedByteReserved.
<--sdRefNumIntegerDriver reference number.

DESCRIPTION
The GetDefaultStartup procedure returns information about the default startup device from parameter RAM. The default startup device parameter block of data type DefStartType defines two kinds of startup devices: either a slot or a SCSI device. The GetDefaultStartup procedure returns in the sdRefNum field a value indicating the startup device type. A negative value indicates a SCSI device. A positive value indicates a slot device. If the value is negative, the sdRefNum field contains the driver reference number needed to identify that device. If the value is positive, the slotDev variant of the default startup device parameter block contains information about the slot device.

You cannot read the system's default startup device parameter block directly. Instead, create another parameter block to which the GetDefaultStartup procedure can write and pass GetDefaultStartup a pointer to that parameter block.

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 specify the default startup device, see the description of the SetDefaultStartup procedure described next.


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6 JUL 1996

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