So if I wanted to best describe the first program that ran on my DEC PDP-11/53 ... then it would have to be:
"Do nothing. Do nothing. Do nothing. Stop."
But at least it worked. I entered those commands as machine instructions in ODT (Octal Debugging Technique) and it ran. Not much of a "Hello World" program though is it?
Here are the details of the instructions:
001000/240<lf> ; NOP
001002/240<lf> ; NOP
001004/240<lf> ; NOP
R6/1000<cr> ; set to start code at 1000
R7/1000<cr> ; set PC to start address so we can use P and not clr PS
RS/340<cr> ; set PS to disable interrupts
P<cr> ; start program
That program was a hacked version of something I found here. Now I need to make it do something better.