Started rethinking how this machine should behave. Updated and refactoring some things with a few new ideas.

misc/another_test.asm

@@ -0,0 +1,3 @@
+some_stub:
+    pop r8
+    jmp [r8] ;return to the calling code.

misc/test.asm

@@ -1,9 +1,11 @@
+.include "/another_test.asm"
+
 .db video_start 0xF37F
 .db msg "Hello, world!", 0
 .db NOTERM "No terminating byte here"
 .db null_byte 0
 
-load r1, [msg] ; Because the lod* instructions can't load an address
+load r1, msg ; Because the lod* instructions can't load an address
                ; from anything but a register, this becomes laa r1, [msg]
 
 ;Routine: string_length
@@ -26,4 +28,6 @@ start:
     jmp start
 
 end:
-ret
+
+pop r8  ;pop the return address from the stack into register 8
+jmp [r8] ;jump to that address