Can you write a hello world program in x86 64-bit assembly?
Of Course! Here's a basic Hello World program in x86 64-bit assembly language:

```perl
section .data
    hello db 'Hello, world!',0

section .text
    global _start

_start:
    ; write 'Hello, world!' to stdout
    mov eax, 4        ; write syscall
    mov ebx, 1        ; file descriptor (stdout)
    mov ecx, hello    ; message to write
    mov edx, 13       ; message length
    int 0x80          ; invoke syscall

    ; exit program
    mov eax, 1        ; exit syscall
    xor ebx, ebx      ; return code (0)
    int 0x80          ; invoke syscall
```



This program defines a string Hello, world! and uses the `write` system call to print it to the console. It then uses the `exit` system call to terminate the program.
Neat, so how can I turn that code into an executable?
To turn this assembly code into an executable, you would need to assemble and link it using a tool such as the GNU Compiler Collection (GCC). Here are the steps:

Save the code into a file named hello.asm.

Assemble the code into an object file using the following command:

nasm -f elf64 -o hello.o hello.asm

Link the object file into an executable using the following command:

ld -s -o hello hello.o

This should produce an executable file named hello that you can run using the following command:

./hello
Note that these commands assume you are using a Linux or Unix-like operating system. The syntax may be different on other operating systems.