From:	NoEmailAds AT execpc DOT com (Chris Giese)
Newsgroups:	comp.os.msdos.djgpp,alt.os.development
Subject:	Help wanted (was Re: 18-sector limit with biosdisk())
Date:	Sat, 24 Feb 2001 19:46:09 GMT
Organization:	PROPULSION GROUP
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Eli Zaretskii <eliz AT is DOT elta DOT co DOT il> wrote:

>On Tue, 13 Feb 2001, Chris Giese wrote:
>
>> Otherwise, I could write a small test program to check if the BIOS
>> really does limit reads to 18 sectors.
>
>That might also be a good idea.

OK, here it is:
	http://www.execpc.com/~geezer/temp/ftest.c
	http://www.execpc.com/~geezer/temp/ftest.exe

Please download it and try it. If it reports that your BIOS
limits INT 13h reads to 18 sectors, let me know.

It compiles with Turbo C 3.0 or DJGPP. The .exe was built with Turbo C.

It needs a "oversized" DOS-formatted floppy with >18 sectors per track.
If you have a non-DOS oversized floppy, there is a #if statement in
the C code that you can change to skip the DOS checks and set the
sectors-per-track to a constant value.

I think error 4 from INT 13h (sector not found) is the only one of
interest here. Maybe let me know, too, if you get error 2 (address
mark not found) or error 0x0A (bad sector).

If you run this program inside a Windows DOS box, no useful
information will be obtained. You're not really using the BIOS
in this case, because Windows services INT 13h with some
protected-mode code in its floppy driver.

Thanks in advance,
Chris Giese

-- 
geezer@    | pmode tutorial, homebrew OS:
execpc.com | http://www.execpc.com/~geezer/os

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