problem with fcb-findfirst

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2 total messages Started by 2ftobelly Mon, 16 Nov 1992 17:32

#756

Author: 2ftobelly
Date: Mon, 16 Nov 1992 17:32

29 lines
1598 bytes

Hi!

I am exploring how DOS works, and especially the file-functions. The
problem is that my reference ("The programmer's PC source book" by
Thom Hogan) seems to contain an error, but I am not sure about this.

When I use interrupt 21h fn 11h (find first file with fcb - I know
that fcb's are outdated, but eg. DIR still uses fcbs) the book says
that the DTA is filled with the drive # and a DIRENTRY structure.

This doesn't seem to be the case, because the first byte of the DTA
after calling fn 11h is 0ffh, which could mean that the DTA is filled
with an extended fcb-structure (opened or unopened?). But I am not sure
about this, also because you also have to supply an unopened fcb (with
ds:dx pointing to it) to this function. 

Does anybody know what the DTA is filled with after a call to int 21h
function 11h?

Thanks in advance for any reply.

Wimjan Jansen van de Laak
(2ftobelly@kuhub.cc.ukans.edu)  

----------------------------------------------------------------------
If our brain was so simple that we could understand it, we would be so
simple that we couldn't.
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Re: problem with fcb-findfirst

#759

Author: Nadeau Jean-Claude
Date: Mon, 16 Nov 1992 21:43

30 lines
1366 bytes

In article <1992Nov16.113211.44824@kuhub.cc.ukans.edu> 2ftobelly@kuhub.cc.ukans.edu writes:
>
>Hi!
>
>I am exploring how DOS works, and especially the file-functions. The
>problem is that my reference ("The programmer's PC source book" by
>Thom Hogan) seems to contain an error, but I am not sure about this.
>
	...

	From Ray Duncan "Advanced MS-DOS", Microsoft Press, 1986.

	Int 21H, function 11H

	"Buffer at current disk transfert area (DTA) address set up an
	unopened normal FCB or extended FCB, depending upon which type
	of FCB was input to function."

	and

	"It is very important to use function 1AH to set the DTA to
	point to a buffer of adequate size before using this call."

	Hope that's help.


-- 
Jean-Claude Nadeau, ing.	<nadeau@ERE.UMontreal.CA>
Services informatiques		Tel. (514) 343-6111,ext 5234
Universite de Montreal		Fax  (514) 343-2155

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