The onboard computer in a 1995 Chevy Astro van isn't a single, easily accessible unit like a modern car's central computer. Instead, its functions are distributed among several modules, primarily within the dashboard and under the hood. There isn't one central location to point to. You'll find various control modules related to engine management (the main "computer" function) in the engine compartment. Other modules related to body control and other functions will be scattered throughout the vehicle.
To access any of these modules would require removing various panels and potentially possessing mechanical knowledge. If you're looking for a specific module, you would need a wiring diagram and a service manual specific to your year and model Astro van.
