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PDP-10.its/doc/hello-midas.md
2020-09-27 19:53:51 +02:00

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# Hello world in MIDAS
Step by step guide on how to create a hello world in MIDAS.
1. Login.
2. Start EMACS (type `: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 channel number.
start: .open ch,[.uao,,'tty] ;Open channel to TTY, for ASCII output.
.lose
move a,[440700,,hello] ;Load A with byte pointer 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` (<kbd>^X</kbd><kbd>^S</kbd>) and exit (<kbd>^X</kbd><kbd>^C</kbd>).
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
The sample program can be found in the HELLO directory.