Compatibility K20D with SMC Pentax-FA 28-80 & 100-300mm?

I have a Z-20 camera with SMC Pentax-FA 28-80 & 100-300mm lenses.
Will the lenses be compatible with the K20D camera?

If they're K Mount, you're good to go.

Very sage advice, Nancy. Learn something new every day.

Thanks fo rthe advice and feedback to all who have responded.
This has answered my question.

All Pentax lenses work with this camera... even the Ricoh ones.

With some old lenses, you will need to use the green button to meter... but that's fine. But ALL lenses will work, and will also have Shake Reduction....

Alan.

I purchased Pentax K200d and lens SMC Pentax FA 28-80 can not work correctly with it.
Do as Nancy Cavender-Garcia says.

Sorry, I was wrong. A ring of apertures of old lens was not in position "A"

I will quote myself:

"With some old lenses, you will need to use the green button to meter"

That's for lenses that are not A (automatic). Such as M or K lenses. The FA and A lenses, can be used both ways... with the aperture ring, and also with the dials, when it's in A position.

First thing to note is that when using K or A mount lenses, integral light measuring is not available. If the camera is set to this it automatically changes to center weighted when fitting these. Spot metering is available too, but not integral.
Secondly, you need to set the focus length for the anti-shake to work properly with these lenses. The K20D promts you to do this when opened up with such lenses fitted.
How to set exposure:
A LENSES: with the aperture ring set to A, they work just like modern DA lenses, and you can use all exposure modes the normal way.The only difference is that AF obviously has to be done manually, and for this the focus confirm beep/light is a great help.
K LENSES: These are a bit more complicated. To use them, you must set custom setting 36:Using Aperture Ring, to 2:permitted (likewise if you want to use the aperture ring on A lenses). Mode dial must be set to M, but this does not mean that the exposure actually has to be set manually. You can either set the aperture and press the green button. This causes the camera to stop down momentarily, take a measuring, and then set the appropriate shutter speed. This way you have aperture priority automatic operation.
The other option is to do your own manual setting. This requires you to set custom setting 30: Preview Method, to 2: optical preview. Holding the on-off button to the right in its preview position stops down the lens, and you may now set the aperture ring to the proper value according to the light measuring bar in the viewfinder. You may want to change the shutter speed instead, but in that case you should make sure to shift shutter speed change in manual to the rear wheel, unless you have extremely flexible fingers!