Linux uses an entirely different method of referencing disk drives to the A:, C: convention used by DOS, Windows, and OS/2. Linux treats devices attached to your system as if they are directories. All devices are attached in the /dev directory.
Floppy drives are attached as fd0, fd1, etc. Your A: drive is therefore /dev/fd0 and your B: drive (if any) will be /dev/fd1.
IDE hard disks are attached as hd and SCSI hard disks are attached as sd. This is then followed by a letter identifying the drive (your first drive is a, the second b, etc and then a number identifying the partition with 1 - 4 representing the four possible primary partitions and 5 onward representing the logical partitions contained within your extended partition. Your C: drive is therefore probably /dev/hda1 if you are using an IDE drive and /dev/sda1 if you have a SCSI drive. If you have multiple operating systems installed in separate primary partitions then the C: drives for each of these (which are normally invisible to one another) are all accessible under Linux (eg. /dev/hda1, /dev/hda2, etc.).
If you have a second hard disk drive (or zip or jaz drive) on your computer then your D: drive will be /dev/hdb1 or /dev/sdb1. If your D: drive is just a separate partition on your first hard drive then it will be /dev/hd5 or /dev/sd5.
Your CD ROM drive (regardless of the drive letter assigned in DOS, windows, or OS/2) is attached as /dev/cdrom.
Note that these are the directory locations where these drives are connected to the operating system. To actually be able to access the files contained on one of these drives in order to read or write to it, the drive needs to be mounted on the system. A drive (file system) can be automatically mounted as either read/write or read only access or may require to be manually mounted before it can be accessed. Drives are normally mounted at Mount Points defined within the /mnt directory and you should go via that directory in order to access the files on any non-linux or removable drives or partitions that you may have.
This article written by Stephen Chapman, Felgall Pty Ltd.