PDP-10.its/doc/hello-midas.md

Hello world in MIDAS

Step by step guide on how to create a hello world in MIDAS.

1. Login.

2. Start EMACS and enter this program. You can skip the comments.

   title hello
   
   a==1                                ;Define two accumulators,
   b==2                                ;A and B.
   ch==1                               ;Output chanel number.
   
   start:  .open ch,[.uao,,'tty]       ;Open channel to TTY, for ASCII output.
            .lose
           move a,[440700,,hello]      ;Load A with byte poiter to string.
   loop:   ildb b,a                    ;Load B from string.
           jumpe b,[.logout 2,]        ;End on zero byte.
           .iot ch,b                   ;Print byte.
   	    jrst loop
   
   hello:  asciz /hello world/
   
   end start				  ;Specify entry point.
   

3. Save it as hello 1 (^X^S) and exit (^X^C).

4. Assemble it with MIDAS.

   :midas ts hello_hello
   

5. Go back to EMACS with ◊P if you need to do edits.

6. Run the program.

   :hello