Inside Macintosh: Operating System Utilities /

Chapter 9 - Start Manager

Using the Start Manager

The Start Manager provides a set of simple routines that get and set information in a word in parameter RAM. This information indicates the default status of some peripheral devices connected to the Macintosh computer. Three of these routines get information about the default startup device, default video device, and the default operating system. Another three routines enable you to set this information. The remaining two routines get and set the timeout interval for the startup drive.

The GetDefaultStartup procedure returns information about the default startup device, and the SetDefaultStartup procedure lets you specify a slot or SCSI device as the default startup device. The default startup device is the drive on which the startup code first attempts to start up the Operating System. The Startup Disk control panel calls the GetDefaultStartup and SetDefaultStartup procedures when the user changes the startup disk. Another pair of routines, the GetVideoDefault and SetVideoDefault procedures, get information about and set the default video device-- essentially, the monitor on which the Macintosh computer displays the message "Welcome to Macintosh" and other startup information. The Monitors control panel calls the GetVideoDefault and SetVideoDefault procedures when the user changes the startup screen. Any changes made to settings in the Monitors control panel take affect at the next system startup.

A third pair of routines, the GetOSDefault and SetOSDefault procedures, enable you to get information about and set the default operating system--the operating system that the processor attempts to initialize and start up. At present, the only default operating systems allowed is the Macintosh Operating System.

The last two routines, the GetTimeout and SetTimeout procedures, get or set the timeout interval for the startup drive. The timeout interval is the interval of time the system waits for the startup drive to respond while the computer is booting. A disk driver might need to change the timeout interval, for example if the drive takes a long time to reach operating speed.