Guy I worked with said he used a mainframe that you had to clock in four 32bit words and then hit run and it would boot. And a newer one where you had to enter

Guy I worked with said he used a mainframe that you had to clock in four 32bit words and then hit run and it would boot. And a newer one where you had to enter one 32 bit word. I think the instruction was like read X byes from the input device port into memory starting at address 1.