Several different programs are used to load COHERENT from a floppy or hard disk into memory. This process is called _b_o_o_t_s_t_r_a_p_p_i_n_g (from the old expression about pulling one's self up by one's bootstraps) or _b_o_o_t_i_n_g for short. The program used depends upon whether one is loading COHERENT from a hard-disk partition, from a 5.25-inch floppy disk, or from a 3.5-inch floppy disk. All of these programs are installed onto your computer during normal installation.
mboot is the master boot program. This is code that resides in the first 446 bytes of the first sector on the hard disk. Because this sector also contains the partition table for the hard disk, mboot is normally written to the hard drive only during installation and only by the fdisk utility.
boot, boot.fha, and boot.fva are variations of the same program. boot occupies the first sector of any bootable hard-drive partition. boot.fha occupies the first sector of a 5.25-inch, high-density floppy disk. boot.fva occupies the first sector of a 3.5-inch, high-density floppy disk.
boot is normally copied to the root partition automatically during installation by a command such as:
/bin/dd if=/conf/boot of=/dev/at0a count=1
In another example, the following commands format and create a file system on a high-density, 5.25-inch floppy disk:
/etc/fdformat -v /dev/fha0
/etc/mkfs /dev/fha0 2400
/bin/cp /conf/boot.fha /dev/fha0
When invoked, boot loads for the tertiary boot program tboot. This, in turn, searches the root directory `/' for file aauuttoobboooott, which is the COHERENT kernel. If it finds this kernel, bboooott loads and invokes it. Otherwise, it gives the prompt _?, and you must type the name of the operating-system kernel to load (typically, ``coherent''). If bboooott cannot find the requested kernel or if an error occurs, boot does not print an error message, but re-prompts with `?'.