Mail Archives: djgpp/1996/04/22/06:39:08
On 22 Apr 1996, Jih-Shin Ho wrote:
> : Not so fast. "Network drives" might mean Novell 3.x, and you'd be
> : surprised to see what you can get there, since Novell 3.x hooks Int 21h
> : before DOS and thus any info about Novell drives bypasses DOS entirely.
>
> If DOS doesn't understand this drive, how can it use the drive ?
> For example, 'dir x:'
Like I said: Novell hooks Int 21h and therefore gets to see any DOS
requests before DOS. If it sees that the request references a disk that
is handled by Novell, it services the request, and DOS might not even know
that such a request was issued.
> But the title is 'detecting drive', not 'detecting valid disk in drive'.
> 4409 only tells you which drive is valid, it can't tell if there is a
> disk in drive.
You don't detect drives as an end in itself. You detect a drive because
you want to do something with that drive after you detected it. What I
wanted to warn about is that when you issue DOS calls that refrence CD-ROM
drives but don't actually access the disk, you could think the drive is
valid, but when you then try to access that drive, you get GPF. For this
reason I think a drive without a disk should be reported as an invalid
drive, or at least some indication of a possible problem should be
available to the caller of such a service.
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