Question

I have the following source snippet from a book that I’m reading now. So I created an asm file and typed exactly. Then used nasm command (nasm -f elf test.asm) then tried to compile into an executable file by using gcc (gcc test.o -o test) then I get the following error.

Error:

ld: warning: ignoring file test.o, file was built for unsupported file format which is not the architecture being linked (x86_64)

Source code:

[BITS 16]

[SECTION .text]

START:
    mov dx, eatmsg
    mov ah, 9
    int 21H

    mov ax, 04C00H
    int 21H

[SECTION .data]

eatmsg  db "Eat at Joe's!", 13, 10, "$"

I guess the source code is not compatible with current generation of CPUs (the book is old…).

How do I fix this source code to run under x86_64 CPUs ?

Answer 1

If you want to continue using that old book to learn the basics (which is just fine, nothing wrong with learning the basics/old way before moving on to modern OS), you can run it in DOSBox, or a FreeDOS VM.