Here is a picture of the IBM 1401 control panel. When the power was turned on, the memory was blank. The computer didn't know anything until some instructions were keyed in by hand. I believe the first few instructions were in Octal. After positioning the switches for an instruction, one would press an enter button. Can't remember which button it was. I believe it took about 5 or 6 separate instructions to tell it to read the tape drive. Then a run button was pushed, I think and if you did it correctly, the tape drive would start reading the tape.
Here was the output card punch, key card punch for input, the computer, the tape drives, don't remember what the next consol was, and finally the printer. And the one I was using had 4K of memory! The good old days.
Good Hunting... from Varmint Al