Here's the DOS COM version. Copy this into HELLO.COM with a hex editor of your choice. It will run in dosbox (that's what I tested on) and should run in Windows

Here's the DOS COM version. Copy this into HELLO.COM with a hex editor of your choice. It will run in dosbox (that's what I tested on) and should run in Windows COMMAND.COM on a 32-bit system. b409ba0d01cd21b44cb05dcd2148454c4c4f20574f524c442124 Here's the breakdown: b409 MOV AH, 09h ; OUTPUT string ba0d01 MOV DX, 010Dh ; address of output buffer (remember we're loaded into 0100h) cd21 INT 21h b44c MOV AH, 4Ch ; TERMINATE with return code b05d MOV AL, 5Dh ; return code cd21 INT 21h 48454c4c4f20574f524c442124 "HELLO WORLD$" ; DOS strings are $ terminated Back in the day we used to do this with the DEBUG.COM command. It's actually not that bad to do this. The thing that sucks is hand assembling and going back to fixup your addresses. It starts to get hairy if you need to flip around the CS and DS registers to shift in different segments. As an exercise for the reader use the RET instruction instead of doing the return code stuff. If you want to really get into you you can look up how to read from the console and then display that string back to the user.