1. Program Requirements

2. Entry Point
Every program needs a well defined entry point _start for the OS to start at
Should be a label called _start
Assembler .global directive used to make it visible outside to outside code

3. Entry Point
Every program needs a well defined entry point _start for the OS to start at
Should be a label called _start
Assembler .global directive used to make it visible outside to outside code

4. Syscalls
SWI 0 used to trigger all system calls:

5. Syscalls
r7 specifies system call to do:

6. Syscalls Basic system call cheat sheet: Std file handles: Stdin = 0
Stdout = 1
Stderr = 2