Date: Tue, 23 Jan 1996 15:46:03 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: "A.Appleyard" <A DOT APPLEYARD AT fs2 DOT mt DOT umist DOT ac DOT uk>
Cc: DJGPP AT sun DOT soe DOT clarkson DOT edu
Subject: Re: Is there a floppy in the drive? (CD-ROM drives)


On Tue, 23 Jan 1996, A.Appleyard wrote:

>   Mine does. I just called DIR on my empty CD-ROM drive, and this happened:-
>   ............................................
> C:\AM>dir e:
> 
> CDR101: Not ready reading drive E
> Abort, Retry, Fail?f
> Volume in drive E has no label
> 
> CDR101: Not ready reading drive E
> Abort, Retry, Fail?f
> Fail on INT 24
>   ............................................

That's exactly what I said: `dir' *does* cause Abort/Retry, but most 
other calls that don't *have* to hit the disk in the drive just silently 
fail.

>   Does this behaviour vary with different CD-ROM drivers or different makes of
> CD-ROM drives?

I didn't test all the CD-ROM drivers out there to know.

Anyway, why do you need to know about all the drives in the system?  
Maybe for your purpose you don't need to know if the disk is in the 
drive?  If you indeed have to know whether there is a disk in the CD-ROM 
drive, check out function 4402h of Int 21h in the Ralph Brown' s 
Interrupt List.  It's subfunction 6 returns device status which has bits 
for door open, no disk in drive, etc.