Adding Kernel file to Floppy

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typedef

Joined: 25 Jul 2010
Posts: 2909
Location: 0x77760000

typedef 04 May 2011, 05:02

I made a simple OS (My first one). And I am using a floppy drive to test it.
I use

Code:

debug
-n boot.bin
-w 100 0 0 1

To write my boot.bin file to the Floppy drive. But then I need to load the kernel which I'll try do by using BIOS function int 13h.

But the question is, how can I write both of the files to the floppy on different sectors because after writing boot.bin to the floppy, I can no longer access it to write the second file.

How did any of you, OS devs, do it ? (Did you use a Floppy)

PS: I want to use the Floppy (No Emulators) and I wan to use int 13h.

Cheers

04 May 2011, 05:02

neville

Joined: 13 Jul 2008
Posts: 507
Location: New Zealand

neville 04 May 2011, 08:42

I remember having exactly the same problem!

I came up with several work-arounds, but the best one was to stop using DOS debug. I use David Lindauer's Get Real Debugger (GRDB) available at http://ladsoft.tripod.com/grdb.htm It reads and writes non-DOS disks quite happily. Most of the syntax is the same as Debug, except for direct disk access! GRDB also has many other nice features.

To write your sectors to floppy disk a:

>grdb boot.bin
-> xw a 100 0 1
-> q

>grdb kernel.bin
-> xw a 100 1A 10
or whatever...

a is the disk drive but do NOT put a colon after it in GRDB.

You can also use GRDB to restore your DOS boot sector of course, which Debug will NEVER allow you to do!

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FAMOS - the first memory operating system

04 May 2011, 08:42

egos

Joined: 10 Feb 2009
Posts: 144

egos 04 May 2011, 16:32

Maybe something like this:

Code:

setupldr fat12 a:
copy kernel.bin a:\

Some years ago I did like you are doing now:

Code:

debug
- N bootcode.bin
- L 7C00
- W 7C00 0 0 1
- Q
copy kernel.bin a:\

04 May 2011, 16:32

typedef

Joined: 25 Jul 2010
Posts: 2909
Location: 0x77760000

typedef 04 May 2011, 18:00

@neville
i still cannot get to write kernel.bin, grdb says error 20C.
and windows reported that a program was trying to access an unknown formatted disk.

btw i'm using XP Home Edition SP3

04 May 2011, 18:00

egos

Joined: 10 Feb 2009
Posts: 144

egos 04 May 2011, 18:55

Save BPB structure (or rewrite it with same values).

04 May 2011, 18:55

Dex4u

Joined: 08 Feb 2005
Posts: 1601
Location: web

Dex4u 04 May 2011, 20:57

I use bootprog, the boot.bin lets you load a mz exe with the name kernel32.exe or kernel32.com.
It keeps the BPB and fat intact so you can load you kernel32.exe onto the floppy like any other file, from windows or linux.

http://alexfru.chat.ru/epm.html#bootprog

Bootprog is written with nasm, i have a fasm ver if you want it.

04 May 2011, 20:57

Enko

Joined: 03 Apr 2007
Posts: 676
Location: Mar del Plata

Enko 04 May 2011, 20:57

Why dont you use a Virtual Machine to test your os?
oracle sun virtualbox, microsoft virtual pc or vmware...

This way, you just need to create your os within a 3 1/4 flopy image.

in vritualpc the size of the disket image should be byte size perfect.
in wmvare could be not exact.

04 May 2011, 20:57

typedef

Joined: 25 Jul 2010
Posts: 2909
Location: 0x77760000

typedef 04 May 2011, 22:02

well, iam trying to avoid emulators right now.

@DEX4U yes, i'd like to have the fasm version.

04 May 2011, 22:02

neville

Joined: 13 Jul 2008
Posts: 507
Location: New Zealand

neville 04 May 2011, 22:43

typedef wrote:

@neville
i still cannot get to write kernel.bin, grdb says error 20C.
and windows reported that a program was trying to access an unknown formatted disk.

btw i'm using XP Home Edition SP3

Oh yes I was working in a pure DOS environment back then. DOS 7.1 = Win98 DOS if I remember correctly. Have you tried running GRDB as administrator? WinXP will be the problem now.

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FAMOS - the first memory operating system

04 May 2011, 22:43

egos

Joined: 10 Feb 2009
Posts: 144

egos 04 May 2011, 22:44

Enko wrote:

This way, you just need to create your os within a 3 1/4 flopy image.

Is it something new? I know 3.5 and 5.25 floppies only Smile

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04 May 2011, 22:44

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20344
Location: In your JS exploiting you and your system

revolution 04 May 2011, 22:51

egos wrote:

Is it something new? I know 3.5 and 5.25 floppies only

Nope, it is not new. It is very old.

04 May 2011, 22:51

typedef

Joined: 25 Jul 2010
Posts: 2909
Location: 0x77760000

typedef 04 May 2011, 22:52

neville wrote:

typedef wrote:
@neville
i still cannot get to write kernel.bin, grdb says error 20C.
and windows reported that a program was trying to access an unknown formatted disk.

btw i'm using XP Home Edition SP3
Have you tried running GRDB as administrator? WinXP will be the problem now.

that means in safe mode. because XP home edition allows admin account only in safe mod. let me try it

04 May 2011, 22:52

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20344
Location: In your JS exploiting you and your system

revolution 04 May 2011, 22:59

typedef wrote:

that means in safe mode. because XP home edition allows admin account only in safe mod. let me try it

You don't need safe mode to run as administrator. Use the "run as" dialog and you can open any program as an administrator.

04 May 2011, 22:59

typedef

Joined: 25 Jul 2010
Posts: 2909
Location: 0x77760000

typedef 04 May 2011, 23:11

nope, still getting the same error 20C

04 May 2011, 23:11

neville

Joined: 13 Jul 2008
Posts: 507
Location: New Zealand

neville 05 May 2011, 00:01

typedef wrote:

nope, still getting the same error 20C

Have you tried right-clicking on Command Prompt and selecting "Run as administrator", then running GRDB from there?
If still no good, maybe the latest version of GRDB is different to the one I used. First get another DOS-formatted FAT12 floppy disk and see if you can write your boot sector with GRDB, using the syntax I gave you before.
I don't recall errors like C20. GRDB used to give four-digit error codes.

_________________
FAMOS - the first memory operating system

05 May 2011, 00:01

typedef

Joined: 25 Jul 2010
Posts: 2909
Location: 0x77760000

typedef 05 May 2011, 01:42

yes the error is 020C

05 May 2011, 01:42

typedef

Joined: 25 Jul 2010
Posts: 2909
Location: 0x77760000

typedef 05 May 2011, 02:53

windows xp home edition does not allow administrator account to run in normal mode.

that is it's behavior. you can go to M$ blogs or forums they'll tell you the same thing.
it is the nature of it's design.

anyways, this is even harder than making a mouse driver.

05 May 2011, 02:53

typedef

Joined: 25 Jul 2010
Posts: 2909
Location: 0x77760000

typedef 05 May 2011, 02:55

oh..i have an idea,,,i'll use two floppy disks.......lol

05 May 2011, 02:55

Enko

Joined: 03 Apr 2007
Posts: 676
Location: Mar del Plata

Enko 05 May 2011, 13:12

typedef wrote:

oh..i have an idea,,,i'll use two floppy disks.......lol

There exist some tools to write flopy disk images on a disket using xp.
I used one to create a win98 recovery disk on a xp pc. I downloaded the tool, and the floppy image.
It was a long time ago, so I don't remember.

But perhaps you should search for a tool to write the entire flopy image. By the way, with this method you could use an emulator with the image too Twisted Evil

05 May 2011, 13:12

Enko

Joined: 03 Apr 2007
Posts: 676
Location: Mar del Plata

Enko 05 May 2011, 13:18

Try this one:

http://www.winimage.com/download.htm

edited:

WinImage is shareware. You may evaluate it for a period of 30 days. After 30 days, you need to register it if you intend to continue using WinImage.

now its wshareware Sad

----------------------------------
http://www.bootdisk.com/bootdisk.htm
in this site, are some windows recovery disk instalations utilities.

http://www.msu-hb.de/download/boot98se.exe
this utility writes the image into the floppy, but ther's a problem, the image is a exe resource.
if you use winrar, it can extract the flopy image from the program. So i think it should be possible using some resource editor like reshack or similar to REPLACE the original image, with one you need.

05 May 2011, 13:18

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