Oh stop groaning. Be thankful that you saw the old Hitchcock movie called " Dail M For Murder ". With Grace Kelly and Ray Milland in it, it was worth seeing. Grace Kelly was always worth seeing.
The N in this case is Nikkormat - one of the long line of successful 35mm SLR cameras from Nikon that were so popular in the 1960's and 70's. More affordable than the Nikon F line from the same makers, it could take the same lenses. In those days the production of cameras with electronics was just coming on - electricity was a new thing - and camera design had frequently to integrate mechanical function with some pretty busy engineering.
The basics that you see today in your digital camera were all there, but a lot of the characteristics were factory-set. Set by the camera factory, makers of the 35mm film, and the people who later developed those films. You were expected to set controls on the camera yourself and set them right; otherwise you were disappointed a week later when the prints and slides returned.
Look at what you were tasked with:
a. Set the ASA. Not the ISO. Same number, different set of bureaucrats. But look at how low and high it goes - 12-1600. No good trying cat in a coal hole action shots, but boy, could you do things with misty motion. Standard slide was 25, standard b/w was 125. No changing once you loaded the film - you were committed to 24 or 36 shots of the same flavour. Choose wisely.
b. Set the shutter speed. You'd quail now at the limitations but they were cutting-edge back then. The position of the control seems odd these days but there were a few cameras that did a similar thing with the film era - some of the Zeiss and Voigtländer models. In any case there is a lever round the left side of the lens mount to shift this ring, and it is firmly detented. That's a mechanical self-timer lever and it works very well.
c. We are no longer in Kansas, Toto - though we might be in Kyoto. Here's where the tentative agreement between electricity and light needs our help. You mounted one of the appropriate Nikon lenses by hooking it into the actuator ring on the mount with that silver bracket on the top into the silver peg. You told the rotating ring what to expect by pulling out the silver bit then cocking it over until it clicked and it followed on after this until you changed lenses. The camera had to know what lens you'd put on there mechanically rather than by electronics. Yes, there were occasional grinding noises.
The silver slider is to push the mirror up for reduction in vibration - the lens release button is nice and firm.
There was enough mechanical force needed for all these actions to cause Nikon to provide that silver milled ring in the middle of the lenses - you could get a good purchase upon it.
Despite what might seem to be the sort of routine that a tank gunner uses loading a shell, the whole system worked well. Nikkormats served many professionals and amateurs for decades - if their electronic cells were still alive they might continue to do so now. The mechanical components were first-rate.