System hangs at boot time

If the boot process hangs after the Kernel: i/o bufs message, the /etc/init file is missing from the system. The /etc/init file contains the init(M) program. Once started, the init process spawns all other processes on the system, so if it is missing, no new processes are started.

To restore /etc/init:

1. Insert the boot floppy disk from the emergency boot floppy disk set in the floppy drive and reboot the machine.

2. Press <Enter> at the Boot: prompt and, when instructed, insert the root floppy disk.

3. Mount the hard disk root filesystem:
   
   /etc/mount /dev/hd0root /mnt

   If mount fails, check the hard disk with the fsck(ADM) command as discussed in ``Checking and repairing filesystems''.

4. Copy the /etc/init file from the root filesystem on the floppy disk to the mounted hard disk:
   
   cp /etc/init /mnt/etc/init

5. Unmount the hard disk:
   
   /etc/umount /mnt

6. With the floppy disk in the drive, reboot the system with the haltsys(ADM) command.

7. Remove the floppy disk from the drive when you see the Press any key to reboot prompt. Press <Enter> at the Boot: prompt to boot from the hard disk.