Floppy programming information... 
Author Message
 Floppy programming information...

Can someone point me into the right direction on working with floppies that
do not have a sector size of 512? Is that a standard, cause I can't seem to
get the computer to boot from a floppy that has a sector size of 1024. I'm
working on an os, and I want to test my bootloader to see if it will work
with different sector sizes. I also need some information on formating the
floppies.

Thanks.



Sun, 08 Aug 1999 03:00:00 GMT  
 Floppy programming information...

Quote:

> Can someone point me into the right direction on working with floppies that
> do not have a sector size of 512? Is that a standard, cause I can't seem to
> get the computer to boot from a floppy that has a sector size of 1024. I'm

To access 1024-byte sectors you need change one parameter which
is kept in memory and pointed to by vector 1Eh (offset 3 from
the vector). Usually it is 2, which mean 512-byte sectors, set
it to 3 for 1024-byte (1=256 byte, 0=1..255, 4=2048, 5=4096...).

Formatting: find description of INT 13h, AH=5 (find pointer in FAQ).
Note the data pointed to by vector 1Eh keeps many floppy parameters
and you must set them correctly (e.g. gap size for format!).



Mon, 09 Aug 1999 03:00:00 GMT  
 Floppy programming information...


Quote:
>Can someone point me into the right direction on working with floppies that
>do not have a sector size of 512? Is that a standard, cause I can't seem to
>get the computer to boot from a floppy that has a sector size of 1024. I'm

        Yes. PC BIOS uses a sector size of 512 bytes as default. You
cannot boot from a floppy with a different sector size.
Quote:
> I also need some information on formating the floppies.

        What specifically do you need to know about formatting
floppies?      


Wed, 11 Aug 1999 03:00:00 GMT  
 Floppy programming information...



Quote:

> >Can someone point me into the right direction on working with floppies
that
> >do not have a sector size of 512? Is that a standard, cause I can't seem
to
> >get the computer to boot from a floppy that has a sector size of 1024.
I'm
>    Yes. PC BIOS uses a sector size of 512 bytes as default. You
> cannot boot from a floppy with a different sector size.

But surely you can make the first track 512Kb and the rest 1024Kb sectors.
Can we?

Quote:
> > I also need some information on formating the floppies.

There's not much documentation lying around. The best reference is in "The
Undocumented PC" from Addison Wesley.

From Vinson ABS.



Fri, 13 Aug 1999 03:00:00 GMT  
 Floppy programming information...

Quote:


> >Can someone point me into the right direction on working with floppies that
> >do not have a sector size of 512? Is that a standard, cause I can't seem to
> >get the computer to boot from a floppy that has a sector size of 1024. I'm
>         Yes. PC BIOS uses a sector size of 512 bytes as default. You
> cannot boot from a floppy with a different sector size.

I haven't tried it, but I believe you can.  I read in my asm book that
BIOS supports 128, 256, 512, and 1024 byte sectors.  I also found that
function 05h of int 13h format's a track with a definable sector size.
Maybe BIOS detects the sector size on bootup somehow, haven't figured
much else out yet.


Sat, 14 Aug 1999 03:00:00 GMT  
 Floppy programming information...

The best way to avoid the problem is formatting the bootsector at 512
bytes and the rest of the track at the size you want. The formating
functions allow to do this, but you need to take special actions to read
or write on a track that has different sector sizes. I have information
how to this, but haven't it at hand. If you are interested, please send
me a mail.

Daniel Mantione



Sat, 14 Aug 1999 03:00:00 GMT  
 Floppy programming information...

Quote:




> > >Can someone point me into the right direction on working with floppies
> that
> > >do not have a sector size of 512? Is that a standard, cause I can't seem
> to
> > >get the computer to boot from a floppy that has a sector size of 1024.
> I'm
> >       Yes. PC BIOS uses a sector size of 512 bytes as default. You
> > cannot boot from a floppy with a different sector size.
> But surely you can make the first track 512Kb and the rest 1024Kb sectors.
> Can we?

Here you have some freeware software you can get information about.

I send you :

- 80x00095.zip (of fidonet).
- You can see the 2M source (how format up to 1.8Mb) in assembler
  It is of ciriaco. http://luna.gui.uva.es/-ciri
  where - is alt+126

- Helppc 2.1

- In the ciriaco page you can get how to program floppy disk without
dma. Maybe you intested too.

  80xxx_95.zip
< 1K Download


Sat, 14 Aug 1999 03:00:00 GMT  
 Floppy programming information...

Even better: format track 0/ head 0 with 512 byte sectors and other tracks
with any size. Why better, it is simple to use BIOS13 to do all the job.
Note: Bootable sector MUST be 512 bytes long. Otherwise POST shouldn't load
it in memory.
--
Branimir Petrovic, Rijeka - Croatia

http://www.iridis.com/bps
-------------------------------------------
Four steps of project:
1. Uncontrolled enthusiasm
2. Understanding that problem has no solution
3. Punishment of all employees under project
4. Award rest employees



Quote:
> The best way to avoid the problem is formatting the bootsector at 512
> bytes and the rest of the track at the size you want. The formating
> functions allow to do this, but you need to take special actions to read
> or write on a track that has different sector sizes. I have information
> how to this, but haven't it at hand. If you are interested, please send
> me a mail.

> Daniel Mantione



Mon, 16 Aug 1999 03:00:00 GMT  
 Floppy programming information...

Quote:

> clip

> clipYou will find your answer in the boot sector data of the floppy.  You

will have to write your own boot sector routine to make it functional.

--
Jerry L. Oyler



Mon, 16 Aug 1999 03:00:00 GMT  
 
 [ 9 post ] 

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