Identifying device files

The device files in /dev have names that correspond to the characteristics of the devices themselves. The following steps show how to work out the name of the device file to use when specifying a floppy disk drive, for example:

1. All floppy disk devices are located in /dev and begin with rfd (the ``r'' is short for ``raw'', because the SCO OpenServer system has to access the disk directly). The ``fd'' stands for floppy disk. So start the device filename with /dev/rfd.

2. If your computer has only one floppy disk drive, follow this with a number ``0''. If your computer has two or more drives, you can follow it with a ``0'', ``1'' or higher number (depending on whether you want to format a disk in the first, second, or subsequent drive).
   

3. Follow this digit with the number of tracks per inch on the disk. This is usually indicated on the disk label. The standard number of tracks per inch on different disks are as follows:

   
   48

   Low-density 5¼ inch disks (360KB)

   
   72

   Double-density 3½ inch disks (720KB)

   
   96

   High-density 5¼ inch disks (1.2MB)

   
   135

   High-density 3½ inch disks (1.44MB)

4. Follow this number with either ``ds'' if the disk is double-sided, or ``ss'' if it is single-sided.

5. Finally, finish the device name by adding the number of sectors per track on the disk, as follows:

   
   9

   Standard 5¼ inch or 3½ inch floppy disk

   
   15

   High-density 5¼ inch floppy disk

   
   18

   High-density 3½ inch floppy disk

A summary of the most common types of floppy disk is given in the following table:

Device code	Size and type of backup media
rfd048ds9	5¼ inch 360KB floppy disk
rfd096ds15	5¼ inch 1.2MB floppy disk
rfd0135ds9	3½ inch 720KB floppy disk
rfd0135ds18	3½ inch 1.44MB floppy disk

Note that all of these entries apply to the first drive (drive 0) on the system. If you want to use the second drive, change the 0 after ``rfd'' to 1; if you want to use the third drive, change the 0 to 2, and so on.