The "chipped" adapters are supposedly "programmable"... but at best all you could do is enter the lens focal length and, maybe, it's max aperture to be recorded in the EXIF of images. Programming the chip doesn't change the functionality of the adapter or the lens in any meaningful way.
Programming the chip may or may not work. I carefully followed the instructions on one, but the EXIF still shows the incorrect focal length and max lens aperture. Also, the "programming" usually just involves selecting among a short list of pre-established, common lens focal length/aperture combos already loaded onto the chip... which may or may not include something that matches the lens you're using.
Still, the chipped adapters are worthwhile.... They allow the camera's Focus Confirmation to work and that can really assist with manual focusing. Personally I think the slightly more expensive chipped adapters are worth it. But there are a couple tricks to using them.
The chip also may be help some cameras recognize that there is a lens installed. Some cameras are set up by default to not shoot, when there's no lens installed (but probably have a setting in the menu to override this). An unchipped adapted lens is like no lens at all, as far as the camera is concerned.
To use Focus Confirmation, the camera must be in One Shot mode (not AI Servo or AI Focus). I also think it works best with Single Point, Manually Selected. It may not be possible to set these with the adapted lens or no lens on the camera. To set both these up, you probably need to have a modern AF lens installed temporarily (at least I've had to do that, with all the Canon camera models I've tried). Once these settings are made, remove the modern lens and install the adapted, vintage lens.
Stopping the lens down actually causes the aperture to close down... dimming down the viewfinder along with it. This also effects Focus Confirmation. It probably varies to some extent with camera model, but I've been able to get Focus Confirmation with as small as f/11 aperture set, in bright lighting conditions (full sun). However, at that small an aperture, the viewfinder will be quite dim, making manual focus difficult.
It can help manual focusing to use Live View. With the lens stopped down very much, it also can help to have Exposure Simulation enabled in Live View. So long as your combo of aperture, shutter speed and ISO allow, that can brighten up the screen in Live View, helping with focus (as well as getting your exposure settings in the ballpark).
I haven't used it, but... as Bob noted too.. I've heard that Magic Lantern's Focus Peaking feature can be helpful with manual focus, too. Of course, that would only work in Live View and M.L. is only fully compatible with select Canon models. Some models it has limited features and others it's not usable at all (see website for list of models and features).
You could manually open the aperture to help with focusing, but keep in mind that the aperture is fully manual too, on an adapted lens. For a correct exposure, you need to set it to the appropriate aperture prior to taking the shot. It's not like a modern lens, where the aperture is held wide open until the very instant of exposure, when it momentarily stops down during exposure, and the re-opens afterward. With an adapted lens, all the stopping down and opening of the aperture is on you and purely manual.
The camera's internal metering system will work as normally with adapted lenses and you can use fully Manual exposure with a "match needle" method, or set the exposure parameters using a separate meter or by eye. Auto exposure is possible, too, with Aperture Priority (Av) mode. I haven't tried it personally, but a second form of auto exposure may be possible using Manual with Auto ISO, on cameras that have that feature. With AE modes, Exposure Compensation also should work and can be used (not all models have E.C. available with Auto ISO, in which case I would avoid using it). Other AE modes Tv and P, and the camera's even more highly automated "Scene" modes or A+ mode CANNOT be used with adapted lenses.
Personally I don't use any adapted M42 mount lenses... but I do use several other adapted mounts and they work similarly.
If I recall correctly, there were several variations of Takumars in M42 mount, as it evolved over the years to add features such as auto aperture (which isn't auto exposure, but simply holds the aperture open until the instant of exposure). The earlier had a "switch" on the side to control the aperture, while the later had that pin in the rear that interfaced with the camera. I imagine the different types of Pentax M42 mount lenses would need different types of adapters, as described by the original poster.
It's great to be able to adapt old lenses for new uses! There are a lot of different mount vintage lenses that can be adapted for use on Canon DSLRs. I'm considering getting an EOS M5 "mirrorless", which expands the list of adaptable and usable vintage lenses even further than is possible with the DSLRs (such as Leica rangefinder L39 or M-bayonet.... Canon FD/FL, too... and more).
More info....
http://bobatkins.com/photography/eosfaq/manual_focus_EOS.html