io without 21h

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Llama Boy

Joined: 24 Jul 2005
Posts: 7
Location: Texas, USA

Llama Boy 26 Jul 2005, 06:11

ok, i know the input and output using 21h, but i dont want it to rely on dos. can i see the code for platform independant INT 21h (ah=9) and INT 21h (ah=0Ah).
Thanks

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26 Jul 2005, 06:11

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20430
Location: In your JS exploiting you and your system

revolution 26 Jul 2005, 06:47

There is no platform independent code for outputting text and inputting keystrokes. You can use the bios INT's 10 etc. but they only work in a real mode OS. Protected mode OS's each have their own style of doing IO and you have no choice but to learn for each OS you want to use.

For Linux - INT 80h
For Windows - API's
For DOS - INT 21h
For BIOS - INT 16h and INT 10h

26 Jul 2005, 06:47

Llama Boy

Joined: 24 Jul 2005
Posts: 7
Location: Texas, USA

Llama Boy 26 Jul 2005, 06:52

well thanks. also, why are most major OSs protected mode?

26 Jul 2005, 06:52

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20430
Location: In your JS exploiting you and your system

revolution 26 Jul 2005, 07:15

Quote:

why are most major OSs protected mode?

Multi-tasking, multi-user, more effective use of the CPU resources.

Have a look at the FASM sources, each supported platform has it's own directory and files to allow the basic IO for use by the core.

26 Jul 2005, 07:15

madmatt

Joined: 07 Oct 2003
Posts: 1045
Location: Michigan, USA

madmatt 26 Jul 2005, 08:42

Llama boy: protected mode allows access to MUCH more memory, better protection of memory resources, and on new processors, allows you to use hyperthreading for faster process multi-tasking, plus the stuff mentioned above

26 Jul 2005, 08:42

shaolin007

Joined: 03 Sep 2004
Posts: 65

shaolin007 26 Jul 2005, 12:48

revolution wrote:

There is no platform independent code for outputting text and inputting keystrokes. You can use the bios INT's 10 etc. but they only work in a real mode OS. Protected mode OS's each have their own style of doing IO and you have no choice but to learn for each OS you want to use.

For Linux - INT 80h
For Windows - API's
For DOS - INT 21h
For BIOS - INT 16h and INT 10h

You could, in real mode that is, write directly to video memory or handle the output by hooking int 09. But why reinvent the wheel unless you have to?

26 Jul 2005, 12:48

Llama Boy

Joined: 24 Jul 2005
Posts: 7
Location: Texas, USA

Llama Boy 27 Jul 2005, 04:48

im guessing protected mode os is much harder to write, seeing as how it gets all these awesome features.

27 Jul 2005, 04:48

smiddy

Joined: 31 Oct 2004
Posts: 557

smiddy 27 Jul 2005, 11:41

Llama Boy wrote:

im guessing protected mode os is much harder to write, seeing as how it gets all these awesome features.

Nah, it isn't harder. It is more time consuming since there are more opportunities for performance and features. Laughing

27 Jul 2005, 11:41

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