SPARC systems have two different types of boot commands available, depending on the version of the system's console PROM. Systems with a PROM version less than 2.0 use what is known as the ``old'' style boot command, while systems whose PROM is at version 2.0 or greater can use either the old or the new style boot commands. If your SPARC system's console prompt is ``ok'', then your system is in new command mode, and can use the new style boot command.
In general, it's preferable to use the new style boot command if your system supports it. Of course, it's possible to use the old style boot command, but you'll need to know a bit more about your hardware configuration. An excellent reference on older Sun hardware in general (and the old-style boot commands in particular) can be found in The Sun Hardware Reference, by James W. Birdsall. It can be found at ftp://ftp.picarefy.com/pub/Sun-Hardware-Ref/parts/. The file part2 contains an in-depth description of the various ``ROM monitors'' present in older Sun Systems.
In general, the new style boot command is boot, followed by a descriptive device name (such as floppy, cdrom, or net).
The old style boot command is b, followed by a device specifier in the form:
Where xx is used to specify the device type (such as sd for SCSI disks), a is the controller number, b, is the device's unit number, and c is the partition number. Please refer to The Sun Hardware Reference if you have an older SPARC system, and require additional information on its boot command syntax.