Found stock certificates need to know values please help

I found these old stock certificates at my mothers house and we are wondering what the values are if any.

American communications and television Inc - 1000 shares ( bought (1988)

ADI electronics - 100 ( bought 1988)

Astro tech international - 3 shares (bought 1989)

We need to know if they split we can see that some have value now but I just don't know how to account for spits and or buyouts etc

Thank you so much for all your help .