Here's a tiny DOS COM file that does it in 18 bytes: ;; 18 bytes DB 'HELLO_WOIY<$' ; executes as machine code, returning SP to original position witho

Here's a tiny DOS COM file that does it in 18 bytes: ;; 18 bytes DB 'HELLO_WOIY<$' ; executes as machine code, returning SP to original position without overwriting return address mov dx, si ; mov dx,0100h MS-DOS (all versions), FreeDOS 1.0, many other DOSes xchg ax, bp ; mov ah,9 MS-DOS 4.0 and later, and FreeDOS 1.0 int 21h ret (credits: https://stackoverflow.com/questions/72635031/assembly-hello-world-execution-file-less-than-20-bytes https://stackoverflow.com/questions/72635031/assembly-hello-...)