ASM Community

Hi everyone !

I'm very, very new at all this programming lark.  But it's just something that grabbed my interest so I thought why not try it out.  Sadly I had a few problems already.

This is about how much I know at the moment:

• A little bit about registers


• A few opcodes mov, jmp, conditional jmps, etc. etc.li]
  

I've done a little programming before but not enough to be mentionable.  I have however done quite a bit of memory editing before which is how I got introduced to asm in the first place.

Right now I intend to just plough through the stuff here:
http://www.asmcommunity.net/board/index.php?action=wiki

But I have a few questions already.  First question is have I got the right software to be learning ASM ?  I just installed "Easy Code Visual Assembler IDE for Masm" and also I 'think' I installed masm but I'm not sure.  There's a folder in the root drive with heaps of stuff in it but there is no other file appearing on the program list.  So where do I go from there to get into the masm program/assembler ?

Oh yeah I'm on Windows Vista so I'm not sure if that affects anything.

Last question is how do I start compiling code ?  From the basics I learnt now, things go in this format kinda:

opcode ,

Is that right or wrong ?  So many questions  :P

Thanks  ;)

Aww I can't learn with Vista without Virtual PC and stuff ?

I tried to compile this:


And it gives this error in the Debug bit:


Btw thanks for replying so quick.

Sorry but could you explain to me the difference between 16 bit and 32 bit please ?  I know it vaguely but it'd be great to get a proper definition from someone who knows their stuff.

Yeah I had a little search already  :P

Thanks so much.  You guys are really helpful.  From what I read it looks like 16 bit is no longer supported really ?  Is there any point in learning it ?  And if not then where can I find tutorials for only 32 bit ?  (Still don't know the difference really  :))

16-bit is dead and useless, imho :)

Don't start off with learning it anyway, it's a bit more complex than 32-bit because of it's limitations, and the need for memorizing a lot of numeric constants for interrupt calls, instead of names and symbolic values for API calls. Once you're on par with 32-bit assembly, you can always pick up 16-bit if necessary.

16-bit is unavailable on all 64-bit windows versions by the way, since there's no hardware support for running 16-bit code in x86-64 mode. You'll need dosbox or a CPU emulator then. But there's still a decent amount of old dos apps that won't work well, since they were written in dirty and very harware dependent ways.

Vista has little to no bearing on writing x86 Windows 32 bit assembly programs.

Writing Win32 assembly programs is to a large degree
a combination of assembly instructions and Windows API calls.

Win32 assembly programs are native code applications,
which run on any of the 32 bit x86 windows OSes
Windows 95, 98, 98SE, ME, NT, 2000, XP, Vista, etc
though different OS versions have varying support of the various API calls.

.NET programs are not written in x86 assembly language but in languages
such as C# or VB.NET and are compiled to .NET IL assembly language then
assembled to .NET bytecode, IL is vastly different and incompatible with x86 assembly.

The .NET runtime is needed for .NET programs to run
and can be used on 2000, XP, Vista and some other Windows versions.

The following code is source for a short MASM example program.
It shows a messagebox then ends.

.686
.MODEL FLAT,STDCALL
OPTION CASEMAP:NONE
include \masm32\include\windows.inc
include \masm32\include\user32.inc
include \masm32\include\kernel32.inc

includeLib \masm32\lib\user32.lib
includeLib \masm32\lib\kernel32.lib

.data
   szMessage0 db "The message:  The number is   0",0
   szMessage1 db "The message:  The number is   1",0
   szMessage2 db "The message:  The number is > 1",0
   szCaption  db "The caption, the titlebar text.",0

.code
start:

   lea edx, szMessage2  ; put the address of szMessage2 into edx
   mov eax, 1           ; put the immediate value 1 into eax
   cmp eax, 0           ; compare eax with 0
   jne M1               ; jump if not equal to label  M1
M0:
   lea edx, szMessage0
   jmp Past             ; jump to label  Past
M1:
   cmp eax, 1
   jne Past
   lea edx, szMessage1
Past:

 ;-------------------- Roughly equivalent using MASM's 
 ;-------------------- built in high level syntax
 ;-------------------- it is replaced with low level code
 ;-------------------- like the opcode version above.
 ;    .if eax == 0
 ;       lea edx, szMessage0
 ;    .elseif eax == 1
 ;       lea edx, szMessage1
 ;    .else
 ;       lea edx, szMessage2
 ;    .endif

   invoke MessageBox, 0, edx, addr szCaption, MB_OK  ; MessageBox API call

   invoke ExitProcess, 0   ; ExitProcess (Program)  API call
end start

As already mentioned the Iczelion tutorial/example programs show how
to code many types of Windows programs.

A reference to Windows API calls is the win32.hlp file that can be found
online, it is written using a C styled syntax but is still applicable to assembly
language programming. Other sources of information are searching the web or searching within assembly language forums.

Depending on the assembler and editor/assembly environment
the steps to create a executable program from assembly source code
can differ substantially from using a command line or batch file
to selecting an item from a menu.

Some of the various assemblers are MASM, FASM, GoAsm, NASM, HLA, YASM
some editor/environments  QEditor, FASMW, Easy Code, RadAsm etc.

I'm writing a new crossplatform and crossarchitecture assembler/compiler/linker tool, and it does/will NOT support 16 bit code, at least unless I am petitioned to implement it.
I have built basic support for late implemention right into the framework regardless, dunno why I bothered ;)