I recently came across a program that looked like a win32 program but going through the source code I came across the interrupt calls like

eventually I realised that it was a native application(the author mentioned it in the comments)

I think I know much about win32 but next to nothing about native windows applications.Are they device drivers or are they ring-0 applications(probably device drivers are ring-0 themselves).

I request to please lead me from where I could learn to write such appications.
And please explain how could we use interrupts, I thought they were obsolete and all we need to know is the api.

please use search function
http://board.flatassembler.net/search.php

native apps can be very funny stuff
http://board.flatassembler.net/topic.php?t=4941

I obviously searched the board before posting the query, but all the search results contained the word "alternative" when I searched for "native",funny?
not for me.

applications using int 3h instructions dont have to be ring0 (since the int3h vector has DPL = 3 .. which means that both usermode and kernelmode programs can use it). debuggers use int 3h instruction to generate EXCEPTION_BREAKPOINT ...

Every int call is not allowed in ring3 where apps are running. When You call int3 your app crashes immediately. BUT! If you run your app under debugger, then debugger treats int3 as a call to break normal app workflow and take control of execution. It is a standard way since int3 always was a call for debugger since early DOS days.

By the way. What is a NATIVE app? Actually NT kernel is just a kernel which does not give a heck about what is running on top. In Windows, NT kernel used inside Win32. Win32 is like a shell on top NT. And You can put other shells! Like POSIX (google for interix) or OS/2 (closed project by MS). And NATIVE app is an app designed for NT kernel, not OS as a whole thing. So NATIVE is not a Win32 app and if Win32 is not loaded then NATIVE can not use Win32 functions. And if you have other shells (called sub-systems by MS) loaded NATIVEs can access their functions (win32 app can not use posix functions directly, only through native app which works like a proxy).

So, basically native apps are nt apps, not win32 apps.

Cross-posting the same questions to multiple forums?

http://www.asmcommunity.net/board/index.php?topic=28765.0

I always post questions to multiple forums to get different point of views on the problem.