[Ham-Computers] Changing Drives When Using DOS

[Jim Hill]

Using a computer running XP Pro.set up with a number of virtual 
drives in an extended partition.

If I start Windows and use Run>CMD to bring up the DOS mode, I see 
C:\Documents and Settings\Jim Hill.  I can change drives by typing 
the drive letter, G: for example.

If I start DOS using a bootable CD, made from a bootable floppy disk, 
I see the A:\> prompt. Typing most other drive letters, C: for 
example,  causes "Invalid drive specification" to appear.  The 
exception is B:, which displays "Insert diskette for drive B: and 
press any key when ready".  I assume the bootable CD is ok because it 
boots and using DIR brings up a list of 13 files including Command.com.

How can I access the C: and other drives when using a bootable disk?

Jim