Flash an led with debug

Is it possible to do this in debug in dos , of course it is . Here is the process for Windows 98 .

1. Open up a dos console . Start / Programs / MS-DOS prompt on my machine.
2. Type in debug on the line displayed on the screen.
3. A - will appear on the next line . After this type in o 378,0 . The led will go out (turn off).
4. Now type in o 378,1 . The led will now go on .


The parameters are as follows
378 is the address you wish to output to , in this case this is the address of LPT1 on my PC . The second parameter is the value to be outputted , this value is in hexadecimal . So for example to switch all of the leds on you would enter o 378,ff .