The PDP-11, a Computer from the Early 1970s

I think they left out a step. Here's the way we did it:

  1. toggle in the bootstrap loader program as they do in the video
  2. run that program to read the tape containing the absolute loader program (that tape looked different from all the others; it was called bootstrap format) the absolute loader was read in to the top end of memory, above the memory used by other programs; this way, it stayed there and you could use it over and over without having to toggle in the bootstrap loader and read the tape again every time; the absolute loader did one thing: read paper tapes and load their contents into memory
  3. run the absolute loader program to read in the editor program
  4. run the editor program to type in, correct, and punch a tape of your program source code
  5. run the absolute loader program again to read in the assembler program
  6. run the assembler program to translate the program source code to binary machine code; this is a two-pass process, so you need to feed the source tape through twice; at the end, the assembler would punch a tape containing the binary machine code for the program
  7. run the absolute loader again to read in the binary tape of the program
  8. if the program needed to read in data, you had to punch that on yet another tape for the program to read (we bought paper tape by the case)

The machine was put together over a period of two or three years to spread the cost out over that time; by the time we had it all together, it was three racks wide, had cost about $65,000, used a couple of kilowatts, and had these components

I got this movie at a meeting where these guys gave a paper describing their use of this ancient computer in their courses; at the end of the presentation, I asked one of them how they kept it in operating condition (computers of that era were notorious for failing and needing repairs). The answer was "eBay". They made the movie when they realized that they weren't going to be able to keep it running forever.