Announce: Assembly FAQs

[Brad Jones]

ASSEMBLY LANGUAGE FAQ
v0.1 (From VBForums' Assembly Language forum.) - 4/30/2001</font></p>

Frequently asked questions

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Contents

• Introduction
• About
• General Questions
  
  • How do I write an assembler program?
    
    • Assemblers
      
    • Hello World!
    • What Now?
  • How Do I Get The Command Line?
  • Links
• Windows
  
  • How do I start programming for Windows?</a></li>
• Contributors</a></li>

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.Introduction

..About

This FAQ was originally created by Jake Bush for VBForums. It has since been updated by people here at CodeGuru

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.General Questions

..How do I write an assembler program?

First you'll need an assembler, see below.

...Assemblers

There are alot of assemblers, but for beginners I would suggest using the A86 assembler. It's free and very easy to use. It doesn't require all the different stuff an average assembler requires. It's for MS-DOS and will only assemble .com files, but it's perfect to learn with. Download it, unzip it and add the directory to the path. Here are some other assemblers...

Turbo Assembler
NASM
flat assembler


...Hello World!

Now that you have an assembler, you'll want to write your first program. The first program people write is usually the "Hello World!" program, so we'll do the same. Create a file and name it "Hello.asm". Then type in the following code...

	jmp	start
Message1	db "Hello World!$"

start:
	mov	ah, 09h
	mov	dx, offset Message1
	int	21h

	mov	ax, 4c00h
	int	21h

Then at the command line type...

a86 hello.asm

You should get "HELLO.COM". Run it and see what happens.

...What Now?

Now that you've written your first assembler program, you want to know what all
that means. We'll for that you'll need to read an assembler tutorial, like these...

Gavin's Guide to 80x86 Assembly
Assembly Programming Journal


..How Do I Get The Command Line?

The command line is loaded in the memory at offset 81h. The length of the command line is at 80h. So assemble this program with A86...

	mov	si, 81h
	mov	ah, 02h

nextbyte:
	lodsb
	cmp	al, 0dh
	je	endload

	mov	dl, al
	int	21h

	jmp	nextbyte

endload:
	ret

This will print out the command line that you type when you run it.

..Links

Easy Assembly
Bob Rich's Tutorials
Gavin's Guide to 80x86 Assembly
Ralf Brown's Interrupt List
The Art of Assembly Language Programming

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.Windows

..How do I start programming for Windows?

First you need to download the MASM32 package at
hutch's home page. Then to start programming for Windows go through the tutorials located at Iczelion's Win32 Assembly Homepage . The tutorials are at
http://members.nbci.com/winasm/tutorials.html . They start very easy, and get pretty hard.

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Contributors

• Jake Bush

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