[MrB]

Go for it, Ron - you've nothing to lose with digital, except a bit of your time!

Any K mount Pentax lens will work on any Pentax K digital body, or their Samsung GX equivalents which also have a K mount - just connect the lens and carry on, as follows:
The F and FA series lenses will auto-focus, but for older lenses use manual focusing - the camera still gives confirmation when correctly focused (it beeps, and also shows the green hexagon in the viewfinder).
When the camera is switched on with an older lens attached, it will ask for the focal length to be entered - this is so that the image stabilisation will work optimally for that lens.
If the lens has an A on the aperture ring, on that setting it will just work normally via the camera controls, in any of the shooting modes.
If it does not have the A setting:- In the camera menus make sure that Using Aperture Ring is Permitted. Set the mode dial to M-Mode and turn the aperture ring to set the desired aperture - in the other modes, the lens will always stay wide open. On models with a green button, pressing it while composing the shot, will set the metered shutter speed for the chosen aperture and ISO. (If no green button, see the camera's User Guide for how to get the light metering values.)

All the best.
Philip