I've written a small back-up program where I use "Int 21h, func 440dh,
minor code 41h" - "Write Track on Logical Drive".
It worked OK in DOS 6 but in Windows 98 SE I've got problems.
Of course I've changed CH to 48h since I use FAT32, and there's no
problem to read tracks from floppys, HDD:s, card readers or whatever
into my image file.
But when I'm trying to write back the tracks to anything but the floppy,
I get the error code "Authorization Problem" via "Get Extended Error".
Apparently Windows demands some permission for me to write on my
own drives!
So - how do I get that permission???
Per Norrby

you can probably use the "lock" command from a command prompt - I don't know how to do this programatically though, but I guess ralf's interrupt list might have the answer.

Thanks for your suggestion.
But the only locking I know about is file locking, int 21h func 5ch.
This is something else, it's that Win 98 stopping me from writing
track by track on my HDD:s. Also, I'm not allowed to use Format
Track on Logical Drive!
It has to be a way to resolve these problems, some int or func
or may be some API to ask Win to give me what authority I need.
May be it would work if I went back to FAT16 but that's just to much.
Like I said - in DOS 6 everything works OK.
Regards , Per N.

hello
i used bios function to read write absolute sectors, it worked under w98 and me,
but be aware that you have to restart your machine to reload data ( if you work on c this means a hard reset, otherwise w can corrupt your data. )

ofcourse direct io access is disabled unless you make a driver.
there are some windows functions to daw sector rw no? scandisk, defrag does it too.

Sorry for the late response, I know this is not in assembler but this is what I used to read the MBR off Windows 2000/XP machines. It is written in C but shouldn't be to hard to convert. I hope it's acceptable to post here..

Doing it with the win32 API is easy (on NT systems, anyway) - the OP wants 16bit code using DOS/BIOS interrupts.

Hello f0dder,
I really do owe you an appology!
You instantly adviced me to use the LOCK command to get
the authority to write directly to all my drives. But
then I couldn't think of anything else but MS-DOS 5's
file locking function included in the SHARE command,
so I didn't take your advice very seriously.
Now I've learned that LOCK isn't what I thought it'd be,
and that I should have listened more carefully to you in
the first place.
My only excuse is that I've been off this kind of
programming for some years.
In the future I'll shurely analyze your tips more
seriously!
Regards,
Per N.

Ps
I'd appreciate to have the possibility to address you
personally.
If that's OK with you, you could leave a PM with your
mail address.
Ds

It's OK, I haven't touched DOS for so long that I thought I might be wrong - have you found what interrupt + func to use, or are you relying on calling command.com's LOCK? I'll PM you my mail address.