>I asked this question a while ago, with little response. Can someone tell me
>how I can create a virtual disk drive under DOS? That is, how do I get DOS
>to think that a certain drive letter is assigned when it really isn't?
"Undocumented DOS" by Schulman et al. Chapter 8 covers the file system
in excruciating detail. To anwer your question in brief, you can create non-
useful drives simply by setting bits in the drive's CDS entry. If you want
the drive to actually do useful things, though, you need to start implementing
IFS functions -- and it rapidly becomes less simple!
The book is published by Addison-Wesley, and the ISBN number is