How do I start learning Assembly

Question

I'd like to play with writing some assembly on my Mac, ideally native, but I'd understand if it's easier to learn in QEMU or something.

I see that there are different dialects of assembly depending on the processor - what dialect is the "best" to learn?

I don't really have any idea of where to start, any pointers as to how to even run a program in assembly?

Answer 1

My suggestion is to act with the best assembler producer out there: gcc.

Write simple programs in C and then compile them with the -S switch. you will get a file.s containing the assembler code. Tinker with it and you will learn it. The best part is that if you want to learn a different assembler, you can just compile gcc as cross compiler, and produce assembler for any supported platform.

Remember to disable optimizations with -O0, otherwise you could find strange tricks.

This is hello world in assembler

    .cstring
LC0:
    .ascii "hello world!\0"
    .text
.globl _main
_main:
    pushl   %ebp
    movl    %esp, %ebp
    pushl   %ebx
    subl    $20, %esp
    call    L3
"L00000000001$pb":
L3:
    popl    %ebx
    leal    LC0-"L00000000001$pb"(%ebx), %eax
    movl    %eax, (%esp)
    call    L_puts$stub
    movl    $0, %eax
    addl    $20, %esp
    popl    %ebx
    leave
    ret
    .section __IMPORT,__jump_table,symbol_stubs,self_modifying_code+pure_instructions,5
L_puts$stub:
    .indirect_symbol _puts
    hlt ; hlt ; hlt ; hlt ; hlt
    .subsections_via_symbols

Answer 2

A few (OK many) years ago I picked up Peter Norton's book on Assembly http://www.amazon.com/Assembly-Language-Primer-Personal-Computer/dp/0136619010. It was a fantastic way to begin assembly programming for the PC. I wonder if you can still get this and use DOSbox to work through it.

Answer 3

Well even though it isn't what some people call the "best" assembly out there, I would recommend learning X86 / X86-64 as it is the most widely used. To run the program, you can simply use GCC to translate it into binary and then run it through your console.