how do BIOS know if floppy driver and disk exist ?

[david]

using int 13h ?

ah = 00h , judge floppy driver ?

ah = 01h,

ah = 02h , judge floppy disk ?

[david]

who can tell me ?

nobody knows ..

di it by myself ..

[JamesM]

You do know that you waited one hour before bumping the thread?

You do realise that people have other things to do than answer your questions and attempt to understand your stinted English?.

I hope so...

[Combuster]

Do you know the meaning of "to search"? There was a reason why your previous threads got STFWed.

Since they say you learn from repeating things:
STFW, STFW and STFW

[david]

to everyone:

i searched the information on google and baidu before i apply this question ...

but no information is useful ...

so i have to ask you

because my english is not good, but i have no method... so i asked

[david]

my computer don't have floppy driver,

i want to forge(伪造) a floppy driver and floppy disk .

system startup, BIOS use int 19h , i want to make int 19h to read floppy disk which i forge(伪造).

i want to hook int 13h achieve .

when system read floppy disk , i make it to read hard disk ... (hook int 13h, ah = 02h, dl = 00h) ..

do you understand ?

chinese language:

我的计算机没有软驱，我想伪造一个软驱和软盘。当BIOS调用int 19hå

[piranha]

wtf?!
OK, I want to know: Who here can read Chinese?

-JL

[david]

I know how to do ..

but thanks all the same

[Combuster]

If you are trying to find out how to do something (as opposed to reporting a bug), begin by describing the goal. Only then describe the particular step towards it that you are blocked on.

Often, people who need technical help have a high-level goal in mind and get stuck on what they think is one particular path towards the goal. They come for help with the step, but don't realize that the path is wrong. It can take substantial effort to get past this.

[JamesM]

[quote="david"]my computer don't have floppy driver,

i want to forge(伪造) a floppy driver and floppy disk .

system startup, BIOS use int 19h , i want to make int 19h to read floppy disk which i forge(伪造).

i want to hook int 13h achieve .

when system read floppy disk , i make it to read hard disk ... (hook int 13h, ah = 02h, dl = 00h) ..

do you understand ?

chinese language:

我的计算机没有软驱，我想伪造一个软驱和软盘。当BIOS调用int 19hå

[JAAman]

BIOS functions are stored in ROM (READ ONLY memory). You can't override them.

yes you can, but in this case, its not a good idea... and to use this for a boot device (as implied by your int19 reference), would require building hardware -- your better off just buying a floppy drive

1) the BIOS cannot detect Floppy disks, instead it relies on the user to tell it which drives you have (you obviously didnt build your own box, so this would have been done by the people you purchased your system from -- although its quite easy to change...)

2) there is only one way to change the operation of int19 -- that is to build a hardware device, with boot-time init code which remaps int19 to your own code, but this wouldnt be a good idea, and int19 doesnt do anything at all with the floppy drive (all it does is tell BIOS to check the next boot device)

3) to trap int13, you will need to load a program to handle the code, then write the address into the RMode IDT

[Brendan]

Hi,

BIOS functions are stored in ROM (READ ONLY memory). You can't override them.

yes you can, but in this case, its not a good idea... and to use this for a boot device (as implied by your int19 reference), would require building hardware -- your better off just buying a floppy drive

There may be another way...

If the computer has CD-ROM and supports "El'Torito" then it should be possible to create a boot CD, where the BIOS pretends the CD is a floppy.

Of course I'd just use a virtual machine instead (Bochs, Qemu, etc), and then start collecting cheap/old computers (e.g. people are often happy to give away old 80486 machines for free).


Cheers,

Brendan