Here is an thorough discussion of Minolta's Maxxum line of auto-focus cameras.
Minolta Maxxum
Here is how you use a manual lens on a Maxxum:
To convert a Minolta Maxxum to manual operation ( and allow the shutter to fire) – mount the lens on the camera and then hold down the mode (button with portrait) and AEL buttons simultaneously while turning the camera on. “OFF” will show briefly in the display – this means that the camera will not keep looking for an electronic signal from the lens, and just fire when the shutter release is depressed.