This is an important point. The MAXXUM cameras and early Sony a-mount cameras (which use the same camera/lens mount) control focusing with a motor in the camera.
All Minolta and Sony A mount cameras have a motor in the body to focus mechanically "screw" driven lenses , not just early Sony A mount cameras .
The newest Sony a-mount lenses use a motor in the lens and are designed for the newest Sony a-mount cameras.
Not just Sony . Some of the later Minolta lenses have the SSM drive in them rather than using the AF drive in the camera body .
Sony just re-badged these lenses when they took over the cameras in 2006 . They later brought out a cheaper in lens AF drive , the SAM lenses .
These will also work on Minolta cameras that can focus SSM lenses , that's the Dynax/Maxxum 7 onwards and and Dynax/Maxxum 9's that have had the SSM/ADI upgrade .
I'm using the Sony CZ 24-70mm f/2.8 SSM and the 70-400mm SSM mk II on my modified Dynax 9 and Dynax 7 , they'll also work fine on my Dynax 4 , Dynax 5 and Maxxum 70 .
So older MAXXUM lenses can only be used on newer Sony cameras with an adaoter, and newer Sony lenses can't be used on older MAXXUM cameras.
All Minolta A mount lenses can be used on all Sony A mount bodies without an adapter .
The only time an A mount lens , SLR or DSLR lens requires an adapter is if you want to use them on an E mount mirrorless digital body .
And yes , Sony SSM or SAM lenses can't be used with AF on cameras before the Dynax 7 from 2000 , although aperture and manual focus work fine , so can be used manually if required .
(Sony also made e-mount cameras and lenses, which are completely different and cannot be used on Maxxum cameras.)
The good news is that there are MILLIONS of MAXXUM and SONY and other lenses that work perfectly well on MAXXUM cameras. The newer MAXXUM cameras and the newer lenses will have additional features -- such as ADI flash capability, but the newer lenses will work fine on the older cameras -- without providing these features.
Another consideration is the change to the electronic flash shoe that Minolta/Sony made. The original MAXXUM cameras used a standard HOT flash shoe, but Minolta modified this and created an iISO flash on their later MAXXUM cameras. Then Sony changed it to another, more advanced style. Each has more features, but need adapters in order to use one with the other.
The first flashes Sony ( HVL-F36AM and 56AM) sold were re-badged Minolta ones ( Minolta 3600HS/d and 5600HS/d )and work with all cameras , film or digital with the iISO hotshoe .
At some point later flashes dropped full support for film cameras and could only function correctly when HSS ( highspeed sync ) was used .
I'm not sure how current MI shoe flashes behave of film cameras , I've not got the flash adapter to go backwards .