There is a big problem with Jay's post. If you check the line voltage with it set for 12 volts DC first and it is actually 120 AC, it will probably fry the meter. Set it for 120 volts AC first and then work down if you need to check this way at all.
A better way to check this is to look for another electrical panel mounted near the primary breaker box. This would contain the relays that the switchs control to turn the 120 volt AC on and off. It should also have some basic info about the system and the manufacturers name. Then check to see if the manufacturer has a web site and find out how to get more info on the system from them.
There have been many manufacturers of such systems over the years. Some people really like them and some people have problems. I think that it is premature to consider changing the system until you know what you have and whether you like it or not. Most electrical/electronic components don't really change much over the years. As long as they are still readily available, the system as it is will probably serve you well for a long time.